I'm new to this, but here goes, I am replacing the head on my 89 jeep commanche 4.0 motor. I see the heads divided up into 87-91, 91-95, and 96-99. However, I keep seeing where people have been doing upgrades and seemed to ignore these and use the different yrs parts interchangeably, because for the most part, it's the same engine, but they are also redoing other parts as well. I found a really, really good deal on a 96 head and I was just wondering, if it was possible to do the swap, if it would be an upgrade by itself, or would the whole intake/exhaust not match up because that would have to be changed too? Any help would be greatly appreciated.

 

Welcome to CF. The manifolds will have to be switched as well, as the port lay-out is slightly different. You'd need to use the sensors from the original head and manifold.

 

If I remember correctly the 91-95 or 96-99 had cracking issues. I remember it being really close to the mid 90s.