Mickey - The original seal is GM# 3746212. The same seal is used for the standard 3 speed in your truck plus it also fits Powerglide transmissions from the same time period. You can find a few NOS seals offered on eBay as well as other vendors with aftermarket replacements. A couple of our usual vendors are listed below.
Jim Carter offers them as a 1955 and later 3 speed/Powerglide/Turbo 350 rear seal under PN: ME505
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
