As far as 89 engine fitting and this or that engine fitting. The renix 87-90 the head will not line up with your intake because of the intake and exhaust ports, but you can swap the head of your engine onto that block. The 91-95 engine are drop in same head and everything (not sure if there were any sensor changes really, but rule of thumb is use the long block keep all of your sensors and accessories just in case), the 96-99 had a different head and only some have the temp sensor hole at the back of the head for the gauge or dummy light, but this can be worked around, and 00-01 are not desirable because of their head cracking, but would work in your vehicle technically. Or in my case I have an 87 block with a 93 head, with a 99 intake with a comp cam. It's all cobbled together. Jeep 4.0s are kinda like legos almost.