Chris, that sucks man.
BTW, if you can drive with the rear locker turned on, but cannot drive when it isn't, pretty likely that you have a broken axle.
The locker on is giving you power to the good side, but with it off, all your power is going to the busted shaft, since that is the path of least resistance.
Probably also the source of the thumping/clicking noise.
Baby Beast 2- 1999 4Runner SR5
Baby Beast -1987 4Runner SR5-Gone, but not forgotten