The part number never shows up on the cover.
The only time you'll see a part number for a cam cover is in the parts books, on a receipt, or on a shipping box.
Part numbers are created to move the product. Casting numbers are created to distinguish the part.
The reason for part number changes (within same casting#s) may simply be for surface finishes for different models or items included with the cover.
Click Here to see a listing of cam cover part numbers in the Sportsterpedia.

The casting number is not the part number.
You'll see multiple year cam covers all with the same casting number but they may have several different part numbers between them.
The reason for casting number changes usually involve different model features needed to be cast into the cover for certain year cases.
Casting numbers can be found on all OEM cam covers on the inside (cam side) of the cover.

L1984-1990 Sportster cam covers: casting number (25222-84A).
1991-1994 Sportster cam covers: casting number (25222-89).
1995-1997 Sportster cam covers: casting number (25230-95).
1998-1999 Sportster cam covers: casting number (25230-98).
2000-2003 Sportster cam covers: casting number (25230-98A).
2004- Sportster cam covers: casting number (25230-04).

1986-2003 cam covers have a circle date code.
The date code represents the machining date (not the year the cover was designed to be used on).
The circle date code consists of a circle cast into the inside of the cover with 12 dividers around the circle representing 12 months of the year.
The last 2 numbers of the year the cover was cast appears in the middle of the circle followed by a series of blots in the divisions around the circle.
You can't interpret the year in the circle to be the year model the cover was made for.
For instance, you may find that a 1990 cover was actually created in 1991 or even 1993 as in the pic below.

L1984-1990 covers:
These all carry the same casting number and judging by casting numbers alone;
The main visual difference between these covers is whether there is a circle date code under the casting number or not.
L1984-1985 casting# (25222-84A) is a standalone number cast on the inside front, not far from the breather valve with no circle date code.
1986-1990 casting# (25222-84A) is in the same spot but all have a circle date code under the casting number (date of casting is in the circle).

L1984-1985 cover casting# (25222-84A) 1)	1986-1990 cover casting# (25222-84A) 2)	Various Date Codes Found on 86-90 Sportster Covers

The same HD part number (25219-86) was used for 1986-1990 cam covers.
The casting number is (25222-84A) for all L1984-1990 cam covers and all have a circle date code below the casting.

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