Screw holes on the tank can help narrow its year.
Some Harley-Davidson enthusiasts enjoy restoring old bikes to their original condition. Sometimes identifying all the antique parts, whether on the bike or not, takes some sleuth work. Harley gas tanks can mostly be identified by the badges on the tank, and in the absence of these the types of screw holes for relief impressions where the badges were once attached. Sometimes these dents are on the bottom of the tanks or between them.
1. Check the frame of the bike for a vehicle identification number, which appeared on all Harley-Davidsons after 1968. This number can pinpoint the year it was made. Use a Harley antique catalog to identify the type of tank manufactured on Harleys that year and compare it with the tank currently on the bike. If the characteristics match, it is likely the tank is original.
2. Look for a fuel shutoff petcock on the top of the left tank. If one is present, the tank was manufactured between 1941 and 1965.
3. Check the tank for emblems. Match any you find in the Harley catalog. If there are no emblems, examine the relief impression left by them. Often, their shapes can still be deciphered in the tank. For example, tanks made in 1961 and 1962 have the relief that held a starburst emblem.
4. Check for strips on the tank that once held an emblem. For example, a strip was spot welded on the tank between 1940 and 1946. Some years produced tanks with additional strips or different shaped strips.