The overdrive section used by Chev Was a Borg Warner that was used by all cars and pickups of that era. The front section can either be GM or the heavy duty one was a Borg Warner front section. Both are good. Make sure you get the entire setup. The relay that is on the firewall sells for $75 to $150 on eBay. Chev used a kickdown switch mounted on the carburetor. Ford and others used a a kickdown switch under the accelerator. The wiring is the same. Don't waste time before the guy changes his mind.