I haven't been able to find a thread where anyone has swapped the HD6L90. Has anyone seen something like that on the internet? Or, and adapter parts? I'm guessing output shafts are different, the transfer case would have to be worked with, custom drive shafts, trans controller, etc.
2007 Denali with the 6l90 that is about to go-
2007 Denali with the 6l90 that is about to go-