Grand Pooh-Bah,
Had the same thing happen to me when I rebuilt my SM420. When you put the clutch shaft in, you had to hold the internal needle bearings in with the little ring clip. When you push the clutch shaft in, the other shaft pushes that retainer clip into a void in the clutch shaft. For some reason that seemed to hang up.
I took a small pipe wrench and put it on the clutch shaft, after I had the front input shaft plate bolted on, and gave it a turn clockwise. Next thing I know, the shaft is turning freely. Have not had any tranny problems in the running truck after doing that.
Just my opinion and any resemblence to the truth is purely coincidental.
BigMac
