Originated from an article by DirtyCory of the XLFORUM ^{1) 2)}
See the 77-85 Oil Pump section of the Sportsterpedia for pics, dims and more information.

Also on this page below;
Parts Lists per Catalogs

There were 4 different pump assembly listings used on Sportsters from 77-85.

1. (26204-75) 1977-1981
2. (26204-82) 82 only
3. (26204-82A) E83 only
4. (26197-83) L83-85

There were 2 different styles of pumps:

1. 77-E83
   • There were 5 different versions of upgrades / changes from 77-E83
2. L83-85
   • This upgraded style oil pump was suggested as a replacement for all year models 77-85
     (parts specific to the older pumps were now obsolete in the 1985 season)

There were 3 part number changes for the body and cover set.
(with unknown casting changes)

• 77-81: (26484-75) Oil pump body, (26486-75) Pump cover
• 82-E83: (26484-83) Oil pump body, (26486-83) Pump cover
• L83-85 (26484-75A) Oil pump body, (26486-75A) Pump cover

The L83-85 style pump will bolt to any 77-85 engine as it's own assembly.
The 77-E83 style pumps should all have interchangeable internals.

Any of the these may be found at swap meets or online.
The only mounting difference being that you might have to change out or work around the fittings.
45° and 90° fittings were changed in some of the different year model pumps.

• 77-81 style oil pump, (1) 90° return and (1) 45° feed fitting.
• 82-E83 style oil pump, (1) 45° return and (1) 45° feed fitting.
• L83-85 style oil pump, (1) 90° return and (1) 90° feed fitting.

Most parts will interchange between the different pumps with the exception of;

Gerotors:

• Either early or late style gerotor gears may be used with late style (under-cut) oil pump bodies and covers.
• 77-E83 style chamfered gerotor gears may (only) be used with early style oil pump bodies and covers.
  (Use of late style gerotor gears in early style oil pump bodies and covers could cause the oil pump to bind up and possible pump failure).
  

Outer Plate:
The outer plate had a design change at the bore for the gearshaft.
The outer plate seal changed to mate up with the new design.
So, they fit together as a unit.
Either plate matched with it's correct seal will work on 77-85 pumps.

• The information below is a compilation of individual year catalogs plus long year span catalogs.
• There were 2 long year span parts catalogs published for sale as the 78 catalog. Both were written years after 1978;
  • The -78A parts catalog was printed in April 1981 and reflects parts available at that time.
  • The -78B parts catalog (printed post IH era) was 'copyright 1989' and reflects parts available then.
    (namely parts that were available in 1985 or later for the 77-85 oil pump, disregarding some - i.e. gerotors as above)
• 1979 and later parts catalogs only reference prior fitment back to 1979.
  (although, many parts will fit 77-78 models)
• The -85A catalog is copyright 1990.

Sold for use on 77-81 engines only. Last sold in 1984.
There were 3 different versions of this pump in regards to upgrades.
Upgrades and parts list versions created thereof are shown below.
The assembly has (1) 90° return and (1) 45° feed fitting.

• New parts / numbers from the -78 parts catalog:
  • New check valve body O-ring (12042) for the '1600' pump only.
    (to account for a possible oversized condition in the check valve bore in the 77 '1600' pump)
  • New check valve (26435-76A).
    • Both the prior and new check valves have the same lower O-ring.
• Discontinued for Parts Order:
  • Original check valve (26435-76) no longer available for parts order.
  • The 1600 pump is no longer produced.
• Notes:
  • 77 check valve body O-ring (26432-76) still available for standard oil pumps.
  • The Oil pressure switch (26554-77) was listed in the -77A parts supplement catalog.
    • However, it was listed as a L77 addition in the -78 parts supplement.
      Previous models had a pressure switch. The circumstance of this switch being a late addition is unclear.
      There was a wiring harness upgrade in 78 and oil pressure gauge available for 77-78 models.
  • Double nuts (7638) for the oil pressure switch also a late addition part #.
    (retainer for the wire to the oil light)

• Discontinued for Parts Order:
  • O-ring (12042) no longer available for parts order.
• Notes:
  • O-ring (26432-76) now the only one available.

• New parts / numbers:
  • Upgraded cover O-ring (26434-76A)
    • This O-ring replaces the original and is used in future oil pumps through 1985.
• Discontinued for Parts Order:
  • Previous cover O-ring (26434-76) no longer available for parts order.

There were no changes to the oil pump noted in the -81 parts catalog.

The new assembly has (1) 45° return and (1) 45° feed fitting.
All other parts are the same as the 81 pump.

• New parts / numbers:
  • The part number changed for the 4 Allen head mounting bolts (3478) although their size didn't change.
• Discontinued for Parts Order:
  • Oil pump mounting bolts (1794).
• Notes:
  • The -82 pump assembly apparently was generated to include the new fitting changes.
    (basically a 81 pump with new fittings)
    • This coincides with the oil tank upgrade in 82 (oil line sizes did not change).
  • New pump assembly was equipped on 82 models.
  • 77-81 oil pump (26204-75), as upgraded, still sold for 81 and prior models (due to the fittings being different in the new assembly).

• New Parts / Numbers:
  • This pump assembly replaced 82 pump (26204-82) for E83 models. Includes;
  • New oil pump body (26484-83).
  • New pump cover (26486-83).
  • New outer plate (26493-75A).
  • New outer plate seal (12036A).
• Discontinued for Parts Order:
  • The 82 oil pump listing (26204-82) no longer available for parts order.

• Notes:
  • 77-81 oil pump (26204-75) still being sold for 77-81 models.
  • 77-81 parts are sold for 77-82 model pumps.
  • New pump assembly was equipped on E83 models and sold as replacement for 82 models.
    • Equipped with the upgrades and 45° oil fittings on both the feed and return hose connections.

The assembly has (1) 90° return and (1) 90° feed fitting.
The new parts in this pump were not sold separately until 1985.

• New Parts / Numbers:
  • Newly designed oil pump assembly (26197-83).
    • The new pump assembly will mount to 77-E83 ^{3) 4)}
    • The gerotor surfaces in the body and the cover are re-designed to accept the L83 gerotors.
      Internal modifications limit interchangeability and affect the installation of repair parts.
  • Upgraded body O-ring (26432-76A)
  • New oil pump body (26484-75A)
  • New pump cover (26486-75A)
  • Upgraded gerotors (L83-85 for the 26197-83) available for parts order:
    • (26491-83) return, set - new part# for 82-85
    • (26492-83) feed, set - new part# for 82-85
    • The new gerotor gears are fabricated without the chamfered top and bottom on the outer diameters as was with the 77-E1983 gerotors.

• Notes:
  
• This pump first appeared in the -84 parts catalog as a replacement assembly unit.
  • It's upgraded replacement parts became available through the -85 parts catalog.
  • During the transition to the L83 oil pump, the MoCo was still producing oil pumps for earlier models:
  • Date references:
    • 99451-84 parts catalog: (copyright August-83).
    • TSB M-860 dated 11-12-1982 (E83 season).
      • The MoCo announces the gerotor gears were then being fabricated without the chamfered top and bottom on the outer diameters.
    • TSB M-892 dated 6-22-1984.
      • The MoCo announces the retirement of the 77-E83 oil pump assembly.
        

• Discontinued for Parts Order:
  • E83 Oil pump assembly (26204-82A) no longer available for parts order.

• Notes:
  • Oil pump assembly (26204-75) and it's upgraded parts still sold for 77-81 models.
  • L83 pump (26197-83) and it's new parts now sold as an assembly only for 82 and up replacement.
  • All parts were still being sold for the 82-E83 and 77-81 pumps.

• Discontinued for Parts Order:
  • 77-81 Oil pump assembly (26204-75) no longer available for parts order.
  • Oil pump body (26484-83) no longer available for parts order.
  • Pump Cover (26486-83) no longer available for parts order.
  • Old gerotor set (26492-75) and (26491-75) no longer available for parts order.
• Notes:
  • L83 oil pump assembly (26197-83) now being sold for 79-85 replacement.
    (as well as shared individual parts along the way with the exception of the E83 gerotors)
  • L83 gerotors now being sold for 82 and up.
    (since you could only now buy the L83 pump body and cover)

-78A (April 1981):

• Lists only parts upgraded by 1981.

-78B (copyright 1989):

• Oil pump “kit” (26197-83) sold for 77 and up models.
• No parts available for any of the prior part specific assemblies.

-85A (copyright 1990):

• Lists the exact same parts as the -85 catalog.

-86 thru -90:
All the parts below are the same as the 85 pump except gerotors;
The -83 return gears are the same but the feed gears had a change.

• Outer plate 26493-75A
• Outer plate seal 12036A
• Spring washer 26461-77
• Gearshaft 26488-75
• Gearshaft pins 26480-77
• Gearshaft retaining ring 26497-75
• Bushing for the pump body 26489-75
• Bushing for the cover 26431-76
• Cover O-ring 26434-76A
• Inner plate 26463-77
• Pump mounting gasket 26495-75
• 90° Return fitting 26496-75
• Return gerotors 26491-83
  (feed gerotors changed, 26492-86).

• Notes:
  • Retainer nuts for the oil pressure switch connector.
    • There was no mention of the nuts on the oil pressure switch.
    • Most likely OEM on 77 models and offered for replacement parts in 78?
    • The -78A parts catalog shows them as a L77 part. ⁵⁾
  • Gerotors.
    • Both feed and scavenge gerotors have a chamfered radius (.020“ x 45° chamfer or .020”) on each outside gearset.
    • The same radius is designed into their respective oil pump body and cover.
    • The gerotor part numbers were used from 77-E83.
    • However, there was a TSB ⁶⁾ regarding the early feed gerotors.
      • The feed gerotors fit inside the oil pump cover and should extend .001” - .005“ above the ridge.
      • This bulletin also says the later feed gerotors should extend up to .011” above the ridge.
    • It is unclear at this point what the difference would have been between the early and late feed gerotors by June of 1977.
    • However, the part number did not change.
  • The special “1600” oil pump.
    • From the Sportsterpedia history section, There was a special “1600” oil pump installed on E1000 engines. ⁷⁾
    • This special (77 only) pump is not listed as a separate item in any of the parts catalogs or supplements.
    • It's possible this was a vendor quality control issue on their casting.
    • A quantity of them had oversized oil pump body 0-rings (which are assembled in the groove in the check valve bore to seal the pump cover).
    • This oversize 0-ring (12042) must be used in place of the standard 0-ring (26432-76) on these pumps only.
    • All such special pumps are identified with the letter “0” stamped on the pump body (exact location unknown).
    • So, the “1600” oil pump (body at least) appears to be the original casting on 77 models.
    • However, it's exact origin and demise is still unclear.

One year production assembly.
The assembly has a 45° feed fitting and a 45° return fitting.
This coincides with the oil tank upgrade in 82.

Production assembly for E83 models.
The assembly has a 45° feed fitting and a 45° return fitting.

L83-85 production assembly.
The assembly has a 90° feed fitting and a 90° return fitting.
This coincides with the oil tank upgrade in 84 (or possibly L83).

This is a compilation of period correct parts cataogs for 77-85 oil pumps.
In addition, the table to the right lists which and how many years each part was used.
New part numbers in each year are highlighted.
All catalogs from 79 and up only list parts to retrofit back to 1979.
However, the chronological list below reveals that 79- means 77- for the most part.

Period correct catalogs;

• 99451-77A supplement catalog
• 99451-78 supplement catalog
• 99451-79 catalog
• 99451-79A catalog
• 99451-80 catalog
• 99451-81 catalog
• 99451-82 catalog
• 99451-83 catalog
• 99451-84 catalog
• 99451-85 catalog

Later year catalogs also referenced;

Some of the parts listed in the later catalogs will be different than the period correct ones.
These catalogs reflect parts that were available at the time of printing.
(which may be upgrades instead original parts).

• 99451-78A (1981)
• 99451-78B (1989)
• 99451-85A (1990)

The -78B and -85A catalogs list the new body and outer plate parts only.
All the parts are for 77-85 pumps which is true.

• Oil pump body (26484-83)
• Pump Cover (26486-83)
• The new body and cover will retro to 77-85 pump (internals).
• Outer plate (26493-75A
• Outer plate seal (12036A)
• The new outer plate will also retrofit to 77-85 pumps (together with updated seal).

But, the only listing for gerotors are the E83 gearset (26492-75) and (26491-75).
It appears the MoCo only offered the L83 gerotors (by themselves) for a limited time after the 1985 season.
Afterwards, the L83 gearset could only be found new in the -83 pump assembly.
The only pump assembly is the 26197-83 as an oil pump “kit” with no way to order the gerotors that fit in it.
(possibly to help to keep them from being installed in the earlier pumps)

Parts list from the -77A and -78 parts catalog supplements: ^{8) 9)}

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(1794)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	77	77-81
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	77	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	77	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	Late 77	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	Late 77	77-85
(12036)	Outer plate seal (between the gerotors)	77	77-82
(12042)	O-ring, body (seals the check valve in the pump body) (from -78)	77 only	77 - 1600 pump only
(26204-75)	Oil pump assembly	77	77-81
(26430-76)	Gear shaft pin	77	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	77	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	77	77-84
(26433-77)	Lower O-ring	77	77-85
(26434-76)	Cover O-ring (between the pump halves)	77	77-79
(26435-76)	Check valve	77	77 only
(26461-77)	Spring washer (between the two plates)	77	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	77	77-85
(26480-77)	Roll pin	77	77-85
(26484-75)	Oil pump body	77	77-82
(26486-75)	Pump cover	77	77-82
(26488-75)	Gear shaft	77	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	77	77-85
(26491-75)	Return gerotor set (thick ones)	77	77-E83
(26492-75)	Feed gerotor set (thin ones)	77	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	77	77-82
(26495-75)	Gasket (pump to engine case)	77	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	77	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	77	77-85
(26554-77)	Oil pressure switch (from -78)	Late 77-78	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	77	77-E83
	45° Return fitting	(not listed)	82-E83

Parts list from the -78 parts catalog supplement: ¹⁰⁾
Part # changes in the table below are highlighted.
(although HD has changed parts without changing the part numbers)

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(1794)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	77-78	77-81
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	77-78	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	77-78	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	Late 77-78	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	Late 77-78	77-85
(12036)	Outer plate seal (between the gerotors)	77-78	77-82
(12042)	O-ring, body (seals the check valve in the pump body)	77 only	77 - 1600 pump only
(26204-75)	Oil pump assembly	77-78	77-81
(26430-76)	Gear shaft pin	77-78	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	77-88	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	77-78	77-84
(26433-77)	Lower O-ring	77-78	77-85
(26434-76)	Cover O-ring (between the pump halves)	77-78	77-79
(26435-76A)	Check valve	77-78	77-85
(26461-77)	Spring washer (between the two plates)	77-78	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	77-78	77-85
(26480-77)	Roll pin	77-78	77-85
(26484-75)	Oil pump body	77-78	77-82
(26486-75)	Pump cover	77-78	77-82
(26488-75)	Gear shaft	77-78	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	77-78	77-85
(26491-75)	Return gerotor set (thick ones)	77-78	77-E83
(26492-75)	Feed gerotor set (thin ones)	77-78	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	77-78	77-82
(26495-75)	Gasket (pump to engine case)	77-78	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	77-78	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	77-78	77-85
(26554-77)	Oil pressure switch	Late 77-78	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	77-78	77-E83
	45° Return fitting	(not listed)	82-E83

Parts list from the -79 parts catalog: ¹¹⁾

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(1794)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79	77-81
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79	77-85
(12036)	Outer plate seal (between the gerotors)	79	77-82
(26204-75)	Oil pump assembly	79	77-81
(26430-76)	Gear shaft pin	79	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79	77-84
(26433-77)	Lower O-ring	79	77-85
(26434-76)	Cover O-ring (between the pump halves)	79	77-79
(26435-76A)	Check valve	79	77-85
(26461-77)	Spring washer (between the two plates)	79	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79	77-85
(26480-77)	Roll pin	79	77-85
(26484-75)	Oil pump body	79	77-82
(26486-75)	Pump cover	79	77-82
(26488-75)	Gear shaft	79	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79	77-85
(26491-75)	Return gerotor set (thick ones)	79	77-E83
(26492-75)	Feed gerotor set (thin ones)	79	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	79	77-82
(26495-75)	Gasket (pump to engine case)	79	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	79	77-85
(26554-77)	Oil pressure switch	79	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79	77-E83
	45° Return fitting	(not listed)	82-E83

Parts list from the -80 parts catalog: ¹²⁾
Part # changes in the table below are highlighted.

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(1794)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-80	77-81
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-80	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-80	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-80	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-80	77-85
(12036)	Outer plate seal (between the gerotors)	79-80	77-82
(26204-75)	Oil pump assembly	79-80	77-81
(26430-76)	Gear shaft pin	79-80	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-80	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79-80	77-84
(26433-77)	Lower O-ring	79-80	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-80	80-85
(26435-76A)	Check valve	79-80	77-85
(26461-77)	Spring washer (between the two plates)	79-80	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-80	77-85
(26480-77)	Roll pin	79-80	77-85
(26484-75)	Oil pump body	79-80	77-82
(26486-75)	Pump cover	79-80	77-82
(26488-75)	Gear shaft	79-80	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-80	77-85
(26491-75)	Return gerotor set (thick ones)	79-80	77-E83
(26492-75)	Feed gerotor set (thin ones)	79-80	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	79-80	77-82
(26495-75)	Gasket (pump to engine case)	79-80	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-80	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	79-80	77-85
(26554-77)	Oil pressure switch	79-80	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-80	77-E83
	45° Return fitting	(not listed)	82-E83

• Notes:
  • There are no changes noted in the -81 parts catalog.

Parts list from the -81 parts catalog: ¹³⁾

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(1794)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-81	77-81
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-81	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-81	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-81	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-81	77-85
(12036)	Outer plate seal (between the gerotors)	79-81	77-82
(26204-75)	Oil pump assembly	79-81	77-81
(26430-76)	Gear shaft pin	79-81	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-81	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79-81	77-84
(26433-77)	Lower O-ring	79-81	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-81	80-85
(26435-76A)	Check valve	79-81	77-85
(26461-77)	Spring washer (between the two plates)	79-81	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-81	77-85
(26480-77)	Roll pin	79-81	77-85
(26484-75)	Oil pump body	79-81	77-82
(26486-75)	Pump cover	79-81	77-82
(26488-75)	Gear shaft	79-81	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-81	77-85
(26491-75)	Return gerotor set (thick ones)	79-81	77-E83
(26492-75)	Feed gerotor set (thin ones)	79-81	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	79-81	77-82
(26495-75)	Gasket (pump to engine case)	79-81	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-81	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	79-81	77-85
(26554-77)	Oil pressure switch	79-81	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-81	77-E83
	45° Return fitting	(not listed)	82-E83

Parts list from the -82 parts catalog: ¹⁴⁾
Part # changes in the table below are highlighted.

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(3478)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-82	82-85
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-82	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-82	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-82	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-82	77-85
(12036)	Outer plate seal (between the gerotors)	79-82	77-82
(26204-75)	Oil pump assembly	79-81	77-81
(26204-82)	Oil pump assembly	82	82 only
(26430-76)	Gear shaft pin	79-82	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-82	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79-82	77-84
(26433-77)	Lower O-ring	79-82	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-82	80-85
(26435-76A)	Check valve	79-82	77-85
(26461-77)	Spring washer (between the two plates)	79-82	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-82	77-85
(26480-77)	Roll pin	79-82	77-85
(26484-75)	Oil pump body	79-82	77-82
(26486-75)	Pump cover	79-82	77-82
(26488-75)	Gear shaft	79-82	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-82	77-85
(26491-75)	Return gerotor set (thick ones)	79-82	77-E83
(26492-75)	Feed gerotor set (thin ones)	79-82	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	79-82	77-82
(26495-75)	Gasket (pump to engine case)	79-82	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-81	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	79-82	77-85
(26554-77)	Oil pressure switch	79-82	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-82	77-E83
	45° Return fitting	82	82-E83

Parts list from the -83 parts catalog: ¹⁵⁾
Part # changes in the table below are highlighted.

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(3478)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-83	82-85
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-83	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-83	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-83	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-83	77-85
(12036)	Outer plate seal (between the gerotors)	79-82	77-82
(12036A)	Outer plate seal (between the gerotors)	83	83-85
(26204-75)	Oil pump assembly	79-81	77-81
(26204-82A)	Oil pump assembly	82-83	83 only
(26430-76)	Gear shaft pin	79-83	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-83	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79-83	77-84
(26433-77)	Lower O-ring	79-83	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-83	80-85
(26435-76A)	Check valve	79-83	77-85
(26461-77)	Spring washer (between the two plates)	79-83	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-83	77-85
(26480-77)	Roll pin	79-83	77-85
(26484-75)	Oil pump body	79-82	77-82
(26484-83)	Oil pump body	83	83-84
(26486-75)	Pump cover	79-83	77-82
(26486-83)	Pump cover	83	83-84
(26488-75)	Gear shaft	79-83	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-83	77-85
(26491-75)	Return gerotor set (thick ones)	79-83	77-E83
(26492-75)	Feed gerotor set (thin ones)	79-83	77-E83
(26493-75)	Outer plate (sits on top of the feed gerotors)	79-82	77-82
(26493-75A)	Outer plate (sits on top of the feed gerotors)	83	83-85
(26495-75)	Gasket (pump to engine case)	79-83	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-81	77-81 L83-85
	90° Feed fitting	(not listed)	L83-85
(26497-75)	Gear shaft retaining ring	79-83	77-85
(26554-77)	Oil pressure switch	79-83	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-83	77-E83
	45° Return fitting	82-83	82-E83

Parts list from the -84 parts catalog: ¹⁶⁾
Part # changes in the table below are highlighted.

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(3478)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-84	82-85
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-84	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-84	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-84	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-84	77-85
(12036)	Outer plate seal (between the gerotors)	79-82	77-82
(12036A)	Outer plate seal (between the gerotors)	79-84	83-85
(26197-83)	Oil pump assembly Late 83 oil pump assembly.	82-84	L83-85
(26204-75)	Oil pump assembly	79-81	77-81
(26430-76)	Gear shaft pin	79-84	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-84	77-85
(26432-76)	O-ring, body (seals the check valve in the pump body)	79-84	77-84
(26433-77)	Lower O-ring	79-84	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-84	80-85
(26435-76A)	Check valve	79-84	77-85
(26461-77)	Spring washer (between the two plates)	79-84	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-84	77-85
(26480-77)	Roll pin	79-84	77-85
(26484-75)	Oil pump body	79-82	77-82
(26484-83)	Oil pump body	83-84	83-84
(26486-75)	Pump cover	79-82	77-82
(26486-83)	Pump cover	83-84	83-84
(26488-75)	Gear shaft	79-84	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-84	77-85
(26491-75)	Return gerotor set (thick ones)	79-84	77-E-83
(26492-75)	Feed gerotor set (thin ones)	79-84	77-E83
(26493-75A)	Outer plate (sits on top of the feed gerotors)	79-84	83-85
(26495-75)	Gasket (pump to engine case)	79-84	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-81 L83-84	77-81 L83-85
	90° Feed fitting	L83-84	L83-85
(26497-75)	Gear shaft retaining ring	79-84	77-85
(26554-77)	Oil pressure switch	79-84	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-E83	77-E83
	45° Return fitting		82-E83

Parts list from the -85 parts catalog: ¹⁷⁾
Part # changes in the table below are highlighted.

Part #	Description	Listed for Year(s)	Factory Installed On Year(s)
(3478)	Oil pump mounting bolt (1/4”x20x2/12“ Allen head) - (4)	79-85	82-85
(6242W)	Oil pump mounting bolt washer (1/4”x9/16“x1/32”) - (4)	79-85	77-85
(7036)	Oil pump mounting bolt lockwasher (1/4“) - (4)	79-85	77-85
(7069)	Oil pressure switch lockwasher (#10) - (2)	79-85	77-85
(7638)	Oil pressure nut (10-32×1/8”x3/8“ hex)- (2)	79-85	77-85
(12036)	Outer plate seal (between the gerotors)	79-82	77-82
(12036A)	Outer plate seal (between the gerotors)	83-85	83-85
(26197-83)	Oil pump assembly Late 83 oil pump assembly.	79-85	L83-85
(26430-76)	Gear shaft pin	79-85	77-85
(26431-76)	Pump cover bushing (AKA lower shaft bushing)	79-85	77-85
(26432-76A)	O-ring, body (seals the check valve in the pump body)	79-85	85
(26433-77)	Lower O-ring	79-85	77-85
(26434-76A)	Cover O-ring (between the pump halves)	79-85	80-85
(26435-76A)	Check valve	79-85	77-85
(26461-77)	Spring washer (between the two plates)	79-85	77-85
(26463-77)	Inner plate (return gerotors sit on this plate)	79-85	77-85
(26480-77)	Roll pin	79-85	77-85
(26484-75A)	Oil pump body	79-85	L83-85
(26486-75A)	Pump cover	79-85	L83-85
(26488-75)	Gear shaft	79-85	77-85
(26489-75)	Pump body bushing (AKA upper shaft bushing)	79-85	77-85
(26491-83)	Return gerotor set	82-85	L83-85
(26492-83)	Feed gerotor set	82-85	L83-85
(26493-75A)	Outer plate (sits on top of the feed gerotors)	79-85	83-85
(26495-75)	Gasket (pump to engine case)	79-85	77-85
(26496-75)	90° Return fitting (3/8” hose nipple)	79-81 L83-85	77-81 L83-85
	90° Feed fitting	L83-85	L83-85
(26497-75)	Gear shaft retaining ring	79-85	77-85
(26554-77)	Oil pressure switch	79-85	77-85
(63540-62)	45° Feed fitting (3/8“ hose nipple)	79-E83	77-E83
	45° Return fitting		82-E83