i have a 77 chevy 3/4 ton 4wd p/u. I was just wondering if a newer (1980 or so) gear driven transfercase will interchange with my aluminum housed chain drive transfer case. The p/u had a manual tranny in it from the factory, but it now has a 3 speed auto. I don't know if the transfer case is the original or not. I just wanted a sturdier transfer case for pulling heavy loads in 4wd because the one in the p/u is jumping under a load. I will take any input on this project. thx