Alrighty then...I just picked up a used top shifting W56 and transfercase that should tide me over, leaving the 4Runner intact. I'll need to convert my crawler box (from the dead G52) to a top shifter, which hopefully will be pretty straight forward. It was years ago when I assembled the crawler, and I can't remember how much I'll have to disassemble to get to the shift rods and forks, but it shouldn't be too bad. I'll probably replace the main seal on the W56's input shaft for good measure.
Any other tips before I dive in?