The three types of mainshafts are early dry clutch (left), early electric start (middle), and late wet clutch (right).
The two early shafts have a hole through them lengthwise to pass the dry clutch release rod. The late shaft is solid, the wet clutch release is in the primary cover.
While the early dry clutch and late wet clutch mainshafts are about the same length, the late model is a bit shorter. The early electric start mainshaft is noticeably longer.
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