When I read a reply that states "Fords worst eng/tranny combo" I believed it. Why, or why not. I need more input. How about electrical issues, timing belt and tensioner, axles, diffs, full time AWD, gas mileage.
There are issues with the heat blend door as I mentioned. It breaks, heat stops, and there are redneck fixes on the board to get it working. The real fixes involve either removing the dash or taking off parts of the A/C system. I think pretty much every ex will have this issue.
no timing belt, I don't think ford has any timing belt products (maybe one or two, but not on the ex). You should replace the idler and tensioner pulley when you get the truck(they do fail), not much harder than changing the belt, and they are maybe $20 each.
The AWD system is pretty maintenance free..If you don't hear any remarkable noises you should get at least 100K more miles out of it at 55K. I would change the fluid in the tcase though, its very easy. The diffs are Ford 8.8s, and we all agree quite heavy duty. Rarely one will implode, but usually at MUCH higher mileage or because water got in. Again, it won't hurt to change the fluid.
Ball joints do wear out, but if they check out fine you should be good to go till at least 100K+. Of course it depends how and where you drive.
Again, the trans in there is pretty bullet proof (4R70w), It goes into other cars and on other forums people abuse the crap out of it and have gone to 200K miles (Its in thunderbirds and we are not easy on them). There is a TSB to update it with some simple things that I highly suggest you do though. You can go even further if you want to drop the valve body and make it practically ideal, but its fine with the simple improvements too.
The 5.0L is a proven engine since the early 60s, I can say I had one go in another car (85 crown vic) go to 240K until a timing gear broke and it jumped time. The new engine probably has a stronger one, and I know many 5.0L exes with 150K+ on that engine. Not saying to do this but I didn't know much about cars with that engine, and I did things like run with low coolant and mix up spark plug wires, and the damn thing ran for many miles. It is a very stout engine, had good compression till the end.
I know I shouldn't say this here but some of the V6 explorers have issues. The 4.0L SOHC has a timing chain issue serious enough to possibly remove the engine if you have it on the rear chain. The V6 5R55E trans has some major issues too, definitely not as durable as the V8 unit.