I did this about 4 years ago in a 95 2 door 4x4 Yukon. I still have it but haven't driven it much.
I replaced the 4L60 with a 4l80 & the stock T-case with a bw4401 (1 ton case).
Different flex plate, had to change the pin outs some & add a few wires to the harness.
It wasn't to difficult.