I've had three 4.0's. 88' XJ that went 275k plus before I put in a rebuild, a 00' WJ that had the piston skirt crack at 105k which I sold and my current 04' WJ with 178k.
Common things I have done as have most of you: Rear Main Seal, rear valve cover leak, belt, T-stat and Radiator, waterpump twice, master cylinder, brakes. Common fluid changes.
Very solid and super simple to work on. My 04' is a Laredo, 242 Tcase, 3" IRO coils, 3/4" KOR spacers and it gets me where we want to go from the beach to the mountains holding all the weight.
Good luck