One of the biggest questions we get when selling engines from our Jeep is "will it fit my specific Jeep."
This list should help with people who have that question. This is for a full bolt-in engine.
The posibility of installing any engine is possible with modification, but this will help you get things together as it should be.

1987-1990 Jeep Cherokee XJ 4.0L
Renix motor - you can use 87-90 4.0L
91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ You will need to relocate temp sender to thermostat housing from HO motor. Also need to use all your Renix accessories, distributor, flywheel/flexplate, etc.
00-01 is not recommended due to crappy head. Some people say the 0331 isn't as bad as people say. We scrap Jeeps, more than likely if we get a 0331 head Jeep in the head is cracked.
Well over half the high mileage 00-01 ones we get in have this problem.

1991-1999 Jeep Cherokee XJ 4.0L
87-90 XJ - Renix motor, lower power output, not recommended
91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ (read 87-90 XJ section above about 0331 head issues on 00-01 XJ)

2000-2001 Jeep Cherokee XJ 4.0L
00-01 XJ
You can also use 91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ engines, but you will need to purchase separate coil pack adapter brackets since the 00-01 is a coil pack motor and earlier engines do not have mounting provisions.
It would be cheaper and easier to just find the correct 00-01 motor.

93-98 Jeep Grand Cherokee ZJ 4.0L
87-90 XJ - Renix motor, lower power output, not recommended
91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ (read 87-90 XJ section above about 0331 head issues on 00-01 XJ)

99-04 Jeep Grand Cherokee WJ 4.0L
99-04 WJ, 00-06 TJ - 2002 and up were TUPY heads and did not have the cracking problems that earlier 0331 heads had. 02+ are recommended.

1991-1995 Jeep Wrangler YJ
87-90 XJ - Renix motor, lower power output, not recommended
91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ (read 87-90 XJ section above about 0331 head issues on 00-01 XJ)

1997-1999 Jeep Wrangler TJ/LJ
87-90 XJ - Renix motor, lower power output, not recommended
91-01 XJ, 93-98 ZJ, 91-95 YJ, 97-99 TJ (read 87-90 XJ section above about 0331 head issues on 00-01 XJ)

2000-2006 Jeep Wrangler TJ/LJ
99-04 WJ, 00-06 TJ - 2002 and up were TUPY heads and did not have the cracking problems that earlier 0331 heads had. 02+ are recommended.