Here is some good information for older transmissions:

http://chev235guy.blogspot.com/search/label/Jumping%20out%20of%203rd%20gear


1953 Chevrolet 3100
261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done
In the DITY Gallery
Video of the 261 running

1964 GMC 1000
305 Big Block V6, sm420, the next cab off restoration