99 Laredo 4L to 01 XJ?

I have a 2001 XJ with select trac. Needs a new engine (spun a crank bearing or bad piston slap, nobody can figure it out). Will a 4.0L from a 99 GC Laredo swap into my Pig? Im not sure if the mounts will mate. Anyone tried this with a Grand swap? I found one with 34K miles on it...will it fit?
Thanks much.

just for fun.... knocking low in the engine (like its coming from the oil pan)on start up, goes away after engine warms up. A can of Restore makes it go away for a few weeks. Then needs more Restore. Oil pressure is fine. exhaust manifold is fine (surprisingly), Head not cracked. Had the Flex plate inspected by two shops and myself. Its tight and fine. One shop says piston skirt cracked, other (dealer) says crank bearing spun. wth? has 137K on it, good power still, just this gremlin.... I have spent the better part of 3 months reading every damn thread on here of this topic lol.

Could be piston slap if it goes away when warm. If so, nothing to worry about. Talyn has changed a few engines and has said that only a 2000/2001 swap without modifications. It can be done. If the engine is good and quiet when hot, I'd keep using it. I thought that spun bearings destroy your oil pressure. And I can't see where spun bearings or cracked piston skirt would quiet down when hot.

I think so too Winter....just sounds so awful, like i have a one-ton diesel. Afraid the rods or pins may be getting worn too....Oil pressure is fine and doesnt burn oil at all. Plenty of power.. I just found a '01 XJ 4L with 70K on it for $700, I may swap it and be done with it. The new engine is down in WI so it may be full of cheese and old No. 4 Jerseys! lol

Problem is you still have the 0331 head. Make sure the WI head is good, then at least you'll have two of them. Have you checked the flex plate bolts?

yah but one nightmare at a time (it never ends) , flex plate and bolts are good. the one shop dropped the tranny a bit so they could get a better look in there. Seller says it all good with a one year warranty. The stupid thing about it was that i didnt want to drop a ton of money into a 8yr old vehicle that has a dead lineage (Chrysler is bankrupt, who knows how long they will make parts), but here I find myself pricing headers and cat-backs and a new Detroit for the D44 to soak up any saving from the engine........there really should be a 1 800 crisis number for Jeepers!!!! endless....

Sounds like piston slap. I've owned about 9 Jeep's now and 3 of them had piston slap. A 1994,1995,1991. It's only on start-up. Low in the engine. Goes away with an oil additive for a bit. Goes away in warmer weather and is more prominent during the winter. Of the 3 I pulled apart two of the engines. It was always the rear piston and it was just slapping the skirt in the wall of the cylinder. I had someone machine out one of them for me and told me he had to cut less than a thousandth to get the mark out of the block.