Morning all I have a 1990 4.0 and a totaled 97 4.0. My question is will every thing "bolt in" I know they changed a lot in 96-01. I ask for the reason that my 1990 took a poop transmission and motor...

 

90 is Renix, 97 is OBD2.
Not a bolt-in swap.

 

The computer only cares about the electronic components. But there are a lot of differences in the accessories and their mounting brackets, and those all have to be dealt with for the everything to mount up properly. Its entirely possible to do it, but its not a direct bolt-on swap, quite a bit of detail work involved.

 

I didn't think it would be easy.. what about a non renix motor, trans and t-case from lIke a 92?

 

The only "bolt on" swap is another engine from an 87-90 XJ. Once you go beyond that it is all pretty much the same difficulty.

 

I swapped a 97 motor into my 87. It would be easier to use your existing trans and t-case. For the engine you need to use the Renix flex plate, intake, and exhaust. Id recommend swapping over to the newer style cooling system without the pressure tank.