Here is a W56 lying beside the Rocky transmission. The W56 is several inches longer, with the shifters 10" further forwards. But the 22R sits about 3-4" further back, which means that I only have to relocate the shifter about 6". I am contemplating welding a great big dog leg in the shifter.
There's also another cross member that will foul the transfer case, the one that holds the torsion bars. I think I'm going to have to cut out the middle and gusset it. I'm gonna need the world's shortest rear driveline; at this point it might be easier to stretch the frame and swap on a Hilux or 4Runner body