In this case, Renix is the name applied to the early years of engine electronics (86-90) with the later years being Chrysler.
To get a 4.0 swap going you will essentially need a complete 4.0 donor MJ/XJ as the 2 powerplants share very little. but you won't be restricted to the old years. you can pick any year XJ/MJ and swap the entire thing in. Plenty of guys have done it.