I believe the only engine choices for the early xj's were the 2.5 4cyl, the 2.8 gm v6(which is junk), and the diesel. If it has the 4.0 in it it has been swapped. If it has a 2.8 in it pass on it big time, it barley has enough power to move it's self let alone pulling a trailer.
If you want a cherokee definitely get one with a 4.0 it will have plenty of power to pull a small trailer, parts are cheap, and they're pretty reliable.
2001 amber fire cherokee sport 4x4, 2 in lift, 30x9.50 generals, 174 ion wheels, pretty much stock.