Jeep tranny's are pretty much bullet-proof, not saying there isn't an idiot out there to ruin one, but for a person who knows how to drive properly they shouldn't have any problems.

The I6 engine is a great engine, it has it's quirks and things that go out, but if you know what will happen you can prevent damage or know what's wrong when it begin's. The oil pump's go out around 100k mile's, what to look for??? oil pressure below 13psi at idle, or below 40psi while under acceleration. The rear main seal is known to go at about 125-175k mile's($500 job) what to look for, oil dripping from rear of oilpan/ transmission.

tranny's are great just make sure you have it flushed and filled regularly. Most jeeps run hot, or most people believe so. 210* is normal for a jeep, w/ a radiator upgrade the temp can be lowered.