sometimes having a mechanic look it over isnt always the best (atleast in my situation). back when i was ready to buy my jeep, my dad took it to a mechanic to get it looked over (he wanted them to look it over). they said that it had a MAJOR electrical problem..they lost everything electrical and it made a loud grinding noise. they also said it had a big oil leak. they said that if i did end up buying it, it would probably only last 1,000 miles if even and i would end up having to put twice the amount i paid for it into it. the result? well yeah, i put twice what i paid for it into it, but in mods and ive had it for over 4,000 miles with only replacing the oil sending unit and u-joints coming up soon.
and the "MAJOR" electrical problem? worn ignition switch. hasnt done it since and if it does happen, i just barely turn the key back and its fine. the big oil leak? its barely leaking at the main seal but not even enough to have to put any oil in before the next oil change. needless to say, i havent been back to that shop and i ended up leaving on a bad note because after they repeatedly tried to tell me not to buy it and just give it to a junkyard, i just shook my head and told them to lay off the weed. and im glad i didnt listen to them..the jeep is still running strong and doesnt show any signs of giving up any time soon.
thats just my experience with corporatley owned auto repair shops. as for what to replace and what not, just look things over and check for leaks and watch the gauges. check the belt for cracks and check the fluids. if its been sitting alot, id just replace all the fluids..
1996 XJ on 36" TSLs, 4", locked F/R, stretched