As I'm sure you're aware, there were very few OD options that allowed the use of the torque tube rear end, and the ones that did exist are scarce beyond belief. For instance, the Truxtell "Tip-Toe-Matic" system replaced the torque tube with a shorter item and put the planetary gearset at the rear of the original transmission. You'll need to acquire a later model open driveline rear axle, and also change the pivoting rear spring mounts for solid ones, with the right pinion gear angle built in as you weld the spring perches onto the axle housing. Don't get tempted to go with a very high ratio rear axle- - - - -Something in the 3.50-3.70:1 ring and pinion ratio will work well with the OD- - - -higher gears will have you shifting in and out of OD too frequently unless the area where you drive is as flat as a pool table. Also, don't get caught up in the fallacy that "all you need is a toggle switch" to make the OD work- - - - -wire the system up properly with a relay and a kickdown switch, using the original Borg-Warner wiring diagram. A Bosch-type relay and a double pole single throw microswitch will substitute for the scarce and expensive OEM parts and work just like the originals.
Jerry
