Both engines will fit but you will need to swap the parts from your engine over to these ones (intake, exhaust, sensors, etc). If you're looking for a direct swap with everything then you'll be looking for '97-mid '99's.
[B]1986 Jeep Comanche 126000+ miles[/B]
Long Bed, Chevy 350 TPI (5.7L V8), AX15, NP231
Roll Bar, 15/38.5R16.5 Ground Hawgs, Bastard lift (Custom 3-link long arm system, 4.5" Rusty's front springs w/ 1.75" spacers and 6.5" RC shocks, SOA rear), Dana 60HP/Sterling 10.25, 4.10's, Recessed winch, more mods to come...
[B]1992 Jeep Comanche 174000+ miles[/B]
Short Bed, 4.0L I6 HO, AX15, NP231
In the process of doing a frame up restoration.
[B]1990 Jeep Cherokee XJ 207774 miles[/B]
4.0L I6, AW4, NP231. Tom Woods SYE and Drive Shaft, Rusty's 8.0" Long Arm Suspension Lift, 36/13.5R15 Super Swamper IROK's, Dana 30 Front, Tube Diff Guard, Dana 44 Rear, 4.56 gears, Ox Locker, disc brake conversion