Watch out for that wiring harness if you swap that engine in. It's different for an XJ than for a TJ! I heard a guy that did it and was successful but ended up saying he wished he had'nt gone that route. Also, the trannies may be different (are they both standards or automatics, both were different from the 2.5l and 4.0l engines). And don't forget about the new exhaust systems you'll have to buy.