Sm420 was last used in 1967.
All trucks 1/2 to 2 ton. 47-67. Chevy and gmc
Just in case someone with a 1947 truck and an "oddball" 4-speed transmission reads this in the future: The SM-420 transmission might have been manufactured by GM from 1947-67 (as shown by Novak), but it was used in 1948-1967 model Chevrolet trucks (probably/maybe in late '47 production, after the 1947 4-speeds ran out of inventory).
