If you really want to know of known problems, check out the TSB and Recalls for the years you are looking at. That will tell you exactly what. I have an '03 and it is holding up pretty good. I have a slight tranny issue I think but other than that, everything else is awesome. The inline 6 is pretty tough. I really can't say anything bad about Jeeps. I mean they have their quarks just like any car....leaks here and there, odd little things, but nothing major. Well worth the money and they hold their value pretty damn well.