If you need a replacement or upgraded oil tank, it's good to know which one is which before you buy one.
1983-2001 oil tanks look very similar when viewing from the front or even side in some cases.
The best way to determine the year model of OEM oil tanks is to look at the rear of the tank.
Looking at the bracing and fitting locations will tell a lot.
There are other details that tell the year model as shown below.

The oil tanks have been upgraded over time to make them stronger at the connection points to their respective battery box.
The weight of the battery is the usual suspect that causes cracks and leaks. Using too much torque on the battery box to tank bolts is another.

Below are the known changes on the rear of oil tanks from 1983-2001.
See this page 1982-1993 Sportster Retrofit Oil Tank Kit (except XR-1000) in the Sportsterpedia for 82-93 oil tank upgrades.

• 1982 oil tank:
  • Standalone welded bracket on the front that mounts to the battery box.
  • Uses the 2-hole battery box with no welded 1/2“ nipple under it.
    The nipple is a drain hose plug and this tank has a drain plug screwed under the bottom of it.
  • 3 oil line fittings
  • Single threaded hole on the upper rear to mount the starter relay to the tank.
  • Curved rear contour.
  • There is no wiring bracket welded to the top.
• 1983-1993 oil tank:
  • Looks almost identical to the 82 oil tank.
  • Standalone welded bracket on the front that mounts to the battery box.
  • Uses the 2-hole battery box with the welded 1/2” nipple under it. The nipple is to terminate the drain plug.
  • 4 oil line fittings
  • Single threaded hole on the upper rear to mount the starter relay to the tank.
  • Curved rear contour.
  • There is no wiring bracket welded to the top.
• 1994-1996 oil tank:
  • Wider front bracket for mounting the battery box.
    Bracket has arms welded to the tank extending to the two front tank to frame rubber mount holes.
  • One piece rear bracket with 2 mounting holes for battery tray. Uses the 3-hole battery box.
  • Only has 3 oil line fittings near on the bottom of the tank.
  • Still has the threaded hole on the upper rear for 82-93 starter relay even though the relay was moved elsewhere in 94.
  • Curved rear contour.
  • Has a thin bracket mounted on top near the rear of the tank for a wire holder.
  • Can be used on 82-93 models paired with the 3 hole battery tray. However, the feed/drain hose may be a tight fit against the frame.
• 1997-1999 oil tank:
  • Looks basically the same as the 94-96 oil tank.
  • Wide front bracket for mounting the battery box.
    Bracket has arms welded to the tank extending to the two front tank to frame rubber mount holes.
  • One piece rear bracket with 2 mounting holes for battery tray. Uses the 3-hole battery box with rubber bumpers on the back wall.
  • 3 oil line fittings on or near the bottom of the tank.
  • Still has the threaded hole on the upper rear for 82-93 starter relay even though the relay was moved elsewhere in 94.
  • Curved rear contour.
  • Feed/drain hose is curved toward the front to give more clearance between the hose and frame.
  • Has a wider bracket mounted on top near the rear of the tank with a hole in the middle of it for a wire clip.
    There is a rubber plug that goes in that hole on 1200S models.
  • Can be used on 82-93 models paired with the 3 hole battery tray.
• 1994-1999 updated oil tank:
  • New version oil tank for 94-99 models (and 82-93 models with the addition of the 94-up, 3 hole battery tray)
  • It's basically the same as the 2000-2003 oil tank with an added threaded hole in the back for the 83-93 starter relay.
  • Requires the 3 hole battery tray.
  • Boxed rear panel design for added strength and less flex with a boxed rear contour.
  • The front battery tray mount was redesigned with a standalone welded bracket (wider base than on 83-93 tanks).
  • Rear battery tray mounts are standalone welded studs with female threads.
  • Has the wide bracket mounted on top near the rear of the tank with a hole in the middle of it for a wire clip.
    There is a rubber plug that goes in that hole on 1200S models.
• 2000-2003 oil tank:
  • The threaded hole for the 82-93 starter relay was deleted.
  • Requires the 3 hole battery tray.
  • Boxed rear panel design for added strength and less flex with a boxed rear contour.
  • The front battery tray mount was redesigned with a standalone welded bracket (wider base than on 83-93 tanks).
  • Rear battery tray mounts are standalone welded studs with female threads.
  • Using this tank on pre-94 models also requires alternate location for starter relay.
  • Has a wide bracket mounted on top near the rear of the tank with a hole in the middle of it for a wire clip.
    There is a rubber plug that goes in that hole on 1200S models.

Pics of battery trays:

• Click here to see pics and info on Ironhead battery trays.
• Click Here to see pics and information on Evo battery trays.

Pics of the rear defining characteristics of the tanks.
Click on any pic below to enlarge:

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Pics of the wiring bracket welded to the top of the tank models near the rear (94-03 models only).

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