From what I understand the early 6 hole drum is not interchangeable with the later 2 hole drum. Can anyone explain why?
Good question, I have wondered that myself. The only thing I can think of is the machined area where the thrust washers ride might be different.
To my knowledge, those holes are for pulling the drum off the transmission shaft. The extra holes give you more flexibility?
The reason I ask is that Lang's suggests using a modified thrust washer set when using the 6 hole hub.
The early hubs are the same, except they are about .015 thousandths more thrust on the hub in the picture that you show.
Put it in a lathe, or mill, and take the .015 off that thrust, and you then can use the Hub, and the three washers.
Herm.
Thanks for your response Herm.