Is it difficult to swap in 4.0 from newer year?

My '91 has about 170k on it and it's a little noisy - I think it's bearings or possibly wristpin or something similar. Anyway, I'm considering a rebuild - I"d definetely make it a stroker, but then last night while searching Ebay I came across lots of healthy engines for pretty cheap. 99,00,01 4.0's w/ anywhere from 70-100k and they were around $500-800. If one was from a Cherokee, would it still bolt-in to my '91? Also, most do not come w/ accesories (alt, starter, etc). What's the likelihood of mine working? Would it be a nightmare w/ the computer? Would I have to swap in the newer computer?

gone postal said:

My '91 has about 170k on it and it's a little noisy - I think it's bearings or possibly wristpin or something similar. Anyway, I'm considering a rebuild - I"d definetely make it a stroker, but then last night while searching Ebay I came across lots of healthy engines for pretty cheap. 99,00,01 4.0's w/ anywhere from 70-100k and they were around $500-800. If one was from a Cherokee, would it still bolt-in to my '91? Also, most do not come w/ accesories (alt, starter, etc). What's the likelihood of mine working? Would it be a nightmare w/ the computer? Would I have to swap in the newer computer?

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I stuck a 99' H.O. into my 89' non H.O. awhile back. Buy a pre 00' because the 00' up had individual coil packs instead of a distributor. I had to use the motor mount ears of my old motor, but it wasn't a problem to take a few parts off my old motor when I needed them. I think I also used the old knock sensor too. I used the 99' intake and header (you'll need to weld in an o2 sensor bung) off of the newer motor and spliced my injector wiring onto the new injectors and used the new throttle body. Since the intake is different I also had to buy a new power steering pump. My old temp sensor was in the head whereas the new one is in the thermostat housing too. I think that was pretty much about it. It should be a little simplier however if you just want to use your old intake, injectors, and throttle body...they will bolt right up to your new motor and you won't have to worry about the power steering or switching anything over (assuming you buy one with the newer style rounded manifold).

From what I hear its not that hard but reuse your electronics. If you have a manual there was a pilot bearing change over. I know where 2 motors are for about $250 here in SC but you have to come and get them.