The "Borg Warner overdrive" is actually a Muncie SM319 3 speed manual transmission with a Borg Warner R10 overdrive. It is an assembly.
They were available in Chevy cars and trucks from 55 through 65. A Saganaw version was available from 66 through 70. To convert for use in a 49 3/4 ton you will need to have your driveshaft modified and either find the column shift linkage for a 3 speed or locate an overdrive specific floor shift conversion kit. There is a wire loom, electrical components, and a cable required.
I specialize in these transmissions. You can send me a PM for more information.
Fred
