Almost all of the 30s-early 60s overdrives in all US brands were Borg Warner R-10 and R-11 units. The R-10 has 3 planetary gears and the R=11 has 4 and is stronger. For different brands the internal parts and operation is the same. The external wiring and switches are brand specific but they all do the same thing.
The cases are specific to brand and the transmissions they used. Parts are mostly available but not easy to find. Check the Studebaker Drivers Club website. I like these overdrives and they are fun to drive once you spend a little time to learn how they work. They can be wired the get OD in all 3 gears or 4 if you want to put one on a Saginaw 4 speed. First you have to to find a Saginaw 3 speed OD.
I am building a 26 Chevy roadster that will run a Borg Warner T86 with a R-10 OD. There are easier and newer ways but this is fun and old timey. They are 30% OD. My '53 Chevy pickup and T5 from and S10. It was easy I already had switched to open driveline.
Glad to see someone keeping a MOPAR flathead six. My dad's favorite engine group.
