Overall they are decent and you need to either A) get a screaming good deal on it or B) get a one owner unit where they can vouch for its service. I've picked up several of these the last few years. Typically I buy them blown engines/tranmissions or accident victims and fix and flip. I've saved a couple for personal use. Mileage on these typically have ranged from 150-325 and prices I've paid are $1200 or less. Some are obviously neglected and pretty nasty inside and out, some just need minor work with incapable owners who won't/can't pay shop prices to fix a list of minor issues.
Big wildcard on these is the cylinder heads on the 4.0 engines. The early 331 castings (found on the rail outside the valve cover next to intake manifold) have some record of cracking. Sometimes on the deck, sometimes between 3-4 valve springs, sometimes both. Milky oil, high pressure in the cooling system,bubbles in the overflow, or gradual overheating are signs of potential issues. Cheap owners will be packing the cooling system with stop leak to overcome these issues. Look for lots of metallic flakes in the radiator as another sign. Or they flat out seized an engine as a result. From my perspective, this isn't a deal killer, but should necessitate a discount. 331 heads with TUPY cast into them under the oil fill cap are a revised version that doesn't seem to have the same issues. Aftermarket heads are available for around $500.
4.0 is an updated design of the 258 AMC, so its a pretty robust unit. Not much really to worry about with these.
Transmission failures are the usual neglecting to deal with leaks and running them low and burning up internal parts.
I've noticed some electric oddities with some of them. Turn the key and a window goes down, rear hatch or door solenoids that won't lock/unlock, wire harness into driver door has breaks in it, radio will loose a channel, console lights fail. Nothing really big unto its self, but things that can be annoying to fix. Crank Position Sensors do occasionally fail and replacing these is a pain in the butt because of its location behind the intake manifold on top of the transmission bell..
Haven't noticed any consistent suspension problems with them. One I have now does have a strange thunk in its front and rear suspension that I have not resolved yet. I've replaced all control arms in it so that's not the issue. I've torn one CV booth, but others have been decent. replaced the half shafts in one because the PO didn't replace torn boots and the CVs were in piss poor shape.
I'm in CO so rust really isn't an issues with these in my area so I can't really advise on this. If anything, dealer or owner add-ons with drilled holes have been the extent of rust I've seen.
They are comfy if you are average in stature. They are a bit small if your a larger dude. They are kind of heavy for their size, around 4500-5000# so they are reasonably safe for their size. Units with leather interiors seem to always be heavily worn inside. Guess not too many people like to take care of their dead cow coverings.
That's about it with what I've seen with this era, referred to in the Jeep world as WJs. Like I said earlier, I've kept a couple of these for my kids to drive, so I'm fairly confident in their reliability and safety.
Quadratech has one of the best selection for parts for these if you don't have a local specialty house.
