|This washer retains the 3rd gear on the mainshaft. It is very similar to a washer on the countershaft, but it is a different diameter and will not interchange.
The final design for this part came in 1956 and it has lasted all through 1984 and probably beyond.
The Iron Sportster mainshaft is a triumph of engineering. The general design has sustained from 1952 to 1984. There were teething problems in the early K-model, but they were all cured by 1957 with the introduction of the Sportster.
The mainshaft washer 3rd gear is in the darker oval.