Hey all,
Here are my videos I took during my SM420 rebuild.
Long video, full overview:

Clutch hub and clutch keys:

Main shaft overview:

Pressing on the clutch hub:

Input shaft needle bearings:


I hope these help. This site has provided lots of helpful info for me, I wanted to contribute back.
Thanks,
Greg


1949 GMC FC253 - 1 Ton Dually
1966 Buick Wildcat Convertible