There is definitely a difference in the gears - it's good to hear that this has been heard of before and has an explanation. The guy I bought it from said it was an M22 - if it's not he said he would give me my money back, so I'm not out any money and gained more knowledge!
The input shaft as well as the cluster gear shaft both have no grooves on them.
Sam - if my memory serves me correct the M22 began to be built in '65 in a very limited quantity and from there to 1969 it was a coarse spline (10 splines) and then from 1970 and up the M22 were fine spline (26 splines) on the input shaft....any body feel free here to correct me if I'm wrong any where I'm just pulling this off the top of my head from something I read a while back....
