Basically, any year 4.0. 87-90 would be a direct swap, as they are the Renix motor. 91-95 are the first generation of HO. They should drop right in. The only problem is the intake or throttle body is different and you'd need to find a place for the knock sensor. Here's a website on hooking up the newer style TB to a Renix motor: http://www.rockmodified.com/2003/april/TB/tb_perf.htm
THe 96-98 are simular to the 91-95 engines. The head doesn't have a port for one of the temp sensors, but that shouldn't be a problem swapping in place of a Renix motor. The 99- and up have smaller exhaust ports but better cam specs. The 99+ heads do crack between the 3-4 exhaust ports. So beware. I put an '03 in my '88 Comanche. Not done yet. The engine brackets had to be modified to work. The '00 block I have has basically the same brackets as my '88. So up to '00 you should be OK. After that, one of the brackets may need to be cut and welded (only one tab)and the other needs just a spacer. SOme say you'll need the header from a later year engine. I have an after market header ( Pace Setter before and Cliford now), so I can't comment on that.
Tom
