[mongocanfly]

Nice truck....if your really wanting a manual I'd keep your current trans or id be looking for a nv4500 and transfer case over a t56...expense is the biggest reason you dont see many..
That t56 is a very long transmision..and the shifter will almost be under the seat if you dont relocate it..
The double od will be useless unless you got some really low axle gears...
it all needs to work together....Engine rpm,tire size,axle ratios,trans gearing
And i dont know if theres a adapter for t56 to pass side drop xcase ...a divorced transfer case would be the best option.....any way you look at it its gonna be expensive...
I would also look for a older LS engine without vvt..but that should be a good engine..just be sure to get everything you need when/if you get it..