This is a transmission rebuild kit for a GM/Chevy Truck with a 4 speed SM420 Transmission Identify this Transmission by 1 PTO opening! This transmission has an iron case that is 10.5" overall length with a cast iron top cover! This Transmission usually comes in the 48-67 GM 1/2, 3/4 Ton or 1 Ton. This kit includes all new bearings, seals, and gaskets!