I believe it was Ruckstell(sp) who made an OD or 2 speed unit that was bolted to the rear end using some sort of an adapter to hook up the torque tube. I actually saw one in place on a 38 Chevy car.I've seen them for sale, big bucks, might be more economical to ditch the torque tube and go with an open driveline and a tranny of your choice.I did this on two of my trucks, fairly simple job.
