Is it a centre slipper you have now or a diff? If you have a diff in the middle and one end is connected to a drive train and the other isn't its always going to spin the end with less resistance, so the free end. If its a slipper and its tight enough you should get drive to the rear wheels, it doesn't matter if there's an out drive on the front or not, not sure about the tc but the db1 uses a modified lazer slipper assembly with the front out drive machined off to provide more room, it would still work just the same even if the unused outdrive was left on, sorry if I have misunderstood your questions though
what's the chassis we're talking about?
(I'm assuming that you have removed the front prop shaft as you want rear wheel drive only from a 4wd chassis)