Used in most upper crank assemblies, and the lower chain drive system found on some units. Most of the crank assembly gears and mechanism ride on this drive shaft. The drive hub extension tube threads onto the second set of threads on this shaft.
Dimensions are 3 3/4" long and 5/8" diameter at it's widest point. This drive shaft has a coarse thread for the 5/8 nut.
Add a matching coarse thread nut here
Part number 4751A3521