[mrbigjeep]

you can find the 8.8's with 4.10's which means you'll have to regear the front. i doubt it will be bolt in because you'll have to weld new brackets and i think explorers were set up for leaf springs in the rear. a tj dana 44 would be much easier to install. it should be a direct bolt in except for the fact that the dana 35 driveshaft might be a little too long.

 

[UCTJ]

I was wanting to throw an 8.8 in the rear of my TJ. What all will have to be done to bolt it in? Also when I go to a junkyard, what should I look for? I know they were in exploders but what years and how can I tell if it is an 8.8? Also how do I know what gears are in it? What other parts will I need to swap it in?

http://www.jeepsunlimited.com/forums/showthread.php?t=674123

This link can give just about all the info you will ever need to build an 8.8.

The 8.8 is not a direct bolt in unless you were to either buy one that was already built by another jeeper or if you bought a new one from www.ok4wd.com which sells them ready to bolt into a TJ.

They can be found pretty cheap and they are only about 5/8" narrower than a TJ axle so the track width is very close. Its been my experience that you will find an 8.8 much sooner, cheaper and more often than a used D44 that you can bolt right into a TJ as most guys do not want to sell that axle. The 8.8 is very strong and has a good aftermarket backing so you can go wrong with it if you went that route.