the ujoint? pull the caliper off, pull the rotor off. there's some 12 point bolts holding the unit bearing onto the knuckle...they thread in from the backside if you're looking at the unit bearing from the side of the jeep. remove those, tap the unit bearing off with a soft hammer, piece of wood, whatever. pull the shaft out. to remove the inner half of the passenger side 2 piece assy, remove the vacuum disconnect on the axle. a good upgrade while you have it apart is to put in TJ shafts. they are one piece and have a slightly stronger ujoint. you have to install a seal inside of the diff housing, which isnt' bad. You mark the bearing caps, remove the carrier assy being careful with the bearings and shims so as not to mix them up, tap the seal into place, and reinstall everything, then cut out a cover where the vacuum disconnect once resided.
if you're mechanically inclined you'll find Jeeps rather simple to wrench on. I'd taught myself a few things and ended up doing high compression engines for street strip honda's, got tired of that and moved onto Jeeps. picked it up quicky and now three years later I'm on my third major build of the Jeep with a near full tube chassis. Only stock parts of the body left are the grill, a new cowl, and a friends hood