How do you know if they are bad? Get someone to shift the Jeep from P-R-D and watch the drive shaft jump around and you will get a clunk. Took two of us about 3 hours to swap it in and out.
Start by unbolting the skid plate which are 4 1/2 inch bolts. 2 in the front that you just loosen and remove the two towards the rear end.
Undo the upper ball joint and tie rod end so you have enough play in the axle out out of the differential the ball joint is an 18mm and the tie rod end is a 21mm IIRC. Take both sides off you will need the play from both sides to reinstall
Next unbolt the drive shaft they should be a 16mm should be 4 of them. Support the weight of the differential and unto the next four bolts shown below. Don't forget the vent tube and electrical connection.
Drop the differential out and and slide if off the axle shaft and drag it out from under the jeep and get it somewhere to work on it.
There's where it was. Now on to getting the old ones out, cut the rubber centers out and cut the old ones into four pieces and fold them into the middle and use a large socket to pound them out or press them out.
The bastard one on the top...
Press the new ones in with a ball joint press, I had to get them half way in with a few different parts and them switch to a pair of channel locks laid across the outer metal and a flat piece on the top of them to finish pushing them in. Make sure they are running front to back and level since it's not a sold bushing.
Reverse to re install it...
Make sure you have some gear oil because you will lose most of it and may as well change it while you have it out. You will need a 14mm bolt and two matching nuts to get the differential fill plug out to refill it looks like this.
I know WK clunks now I have fixed them all.