Not to hyjack a thread but I have a 1977 GMC that I've installed a 2000 H1 6.5TD with 4l80e trans. I used a B/W transfer case from a Revcon MH and went forward to a 2012 9.25" AAM front diff out of a one ton Chevy. We've put about 3000 miles on it since September and have very few nit's to pick so far.
Not a swap for the faint of heart for sure, but a nice match.
Hal