Originally Posted by Shawty
That is an axle nut, it is either a 32mm, 34mm or 36mm, I can't remember exactly. If you have the Jeep in 4wd and in park the shaft won't spin. Spray it down really good with PB blaster and let it sit for a few minutes then use the axle nut socket and a breaker bar and it should come off no problem.
If that doesn't work I have had to use some head and heat the nut up to get it off, but that is rare.
After you get it out, be extremely careful removing the axle shaft because you don't want to damage the seals inside the axle tube.
Once you are going to change the U-Joint, put it in a vice and use a socket on the caps and hit it with a decent sized hammer until the opposite side comes out. Then do the same for the other caps.
Them install the new joint, put the shat back in the axle tube, again be careful of the seals inside the axle, bolt the shaft back up. Put the brakes back on and you should be good to go.
If you have any other questions shoot me a PM and I will get you taken care of.