yup, the whole shebang from the '88 will bolt right in. the only difference is that the '88 uses a top shifted transfer case, while the '91 has a forward shifted case. to go to a dual case setup you'd either have to use your current tranny and t-case(for a crawl box) and bolt the '88 case behind that, or change your current case over to top shift(about $60 if you want it to be a crawl box for duals) to run it behind the '88 tranny
