Borg Warner overdrive in Model A and Early V-8's

[bullrunmotor]

I recently saw a 28 Model A and 34 Ford V-8 in a collection of cars that dated back to the 60's which had Borg Warner overdrives fitted to them. They still had closed drive shafts. The owners son told me that this was a popular conversion back in the day. The former owner was a talented machinist. I've heard of a Laycock overdrive conversion-like MG's and Volvos had in them. Is anyone familiar with the Borg Warner conversion? It sure looked slick. Thanks in advance.