Have you ever wondered how you could run an early Ford closed drive shaft from that early banjo rear with a later overdrive transmission? Well, there is one guy that has made this possible with a nice little adapter. Keep that period looking rear axle assembly and Flathead, or whatever power plant suits your fancy, and run a GM T5 transmission with his adapter and you can have your cake and eat it too.
Dan Bridges of Orange, California, has put together a cast aluminum and machined adapter along with the other components you will need to use your junkyard S-10 4x4 T5 overdrive transmission and your stock type closed driven rear end. The adapter and components are a simple solution to a complicated adaptation. Absolutely genius. The adapter is engineered and machined to high-tolerances and will withstand about anything you throw at it. Dan drives his everywhere behind a highly modified Ford B-banger. Rather he's hauling down the highway (I've experienced this first hand) or pulling low numbers at the drag strip, it will handle the abuse.
For more information on Dan's drive line adapter, you can contact him at firstname.lastname@example.org. I think you will find the price to be very reasonable for the amount of effort it takes to produce this conversion.