The "torque tube overdrives" were somewhat common many years ago but for the most part they are unobtainum. There is an article on them in Tom Brownell's book "How to restore your Chevrolet pickup" which was printed some time back. A B/W or other OD assy was incorporated into the torque tube which required extensive machining, welding, and skills. I have seen them on Model A's and a friend had a 46 Ford ragtop that had one installed. You would be better off converting to an open driveline where you would have more options.
Fred
