weak point is the unibody construction and dana 35 rear ends. Keep a look out for the chrysler rear instead. they are way stronger than the dana 35 and bu tnot as good as the dana 44, which don't happen often in newer cherokees.The way to tell is part of the pumpkin on the crysler rear sticks out below the cover whearas the d35 don't.
As far as mods go there are tons out there but you can't do a body lift due to the unibody construction.Alot if not all performance mods are BS unless you have a high poewered jeep engine that your running at high revs most of the time.