Occasionally you will find drive and driven gears for the sm420 on ebay. Make sure you match the pitch, both drive and driven gears must have the same pitch or they will eat each other. Tell me your what you have/need and I will look through my parts.
Steve


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