The clutch hub attaches to the transmission input shaft. There were four types, one for the 1952 and 1953 5-plate clutch. The next was for the 7/8 plate dry clutch used from 1954 to 1970 XLCH. THe 1967 to 1970 electric start model got a different hub to work with the dual-row Torrington bearing in the shell (basket). Finally there was the wet-clutch hub used from 1971 onwards.
Used on the 1952 and 1953 K-models.
Used on 54 tp E57 SPortsters
Used on Late 1957 to 66 all, 67-69 XLCH
Used on 1967 to 70 XLH, 70 XLCH
Use on teh wet clutch bikes since 1971