I believe both those motors use the 4L60/65E transmissions. So yes your 5.3 transfercase will work with it but I am not sure where the brains for the auto transfercase lies. If it uses a seperate puter then you are good to go. If it is buried in the truck's puter then you may need a different one of those. Either way why not put an older stick operated transfercase in there for better reliability for your beast? Although not sure how the computer would deal with that either. Isn't problems like these why you have a fab shop?