If you don't plan on doing gears on anything else it probably isn't worth it to do it yourself unless you've already got the tools to do it yourself. But if you had the tools to do it yourself you probably wouldn't be asking. If you have to buy all the special tools needed to do it right and in a reasonable amount of time it will cost you less to pay someone else to do it.
2012 Silver Sport S, Silver, 6 speed, soft top, 3.73s, LSD, PCG, Infiniti, deep tint windows, Pro Comp 1028 wheels, 33" Duratracs, Smittybilt bumpers and steps, KC fog lights, Mopar slush mats and fuel door.
I've done them. There is a pinion gear with bearing and crush sleeve. There is a preload on the bearing, which ultimately give you proper loading and pattering on the ring and pinion.
If you screw this up, you will toast the rear end within 50 miles.
Separately there is/may be a shimming of the carrier. That's the guts of the pumpkin. The carrier holds the ring gear - it may be an LSD, Detroit, ARB, Eaton, Auburn, etc.
In a nutshell, if all is too tight (no play) you'll burn a bearing, it'll get sloppy, and will probably ruin the ring and pinion. Too much slop, and you'll hear a clunk, it'll ruin the ring and pinion. The pattering is how they mate - normally there is a "feelable" play.
Not sure, take it to a shop that does rear ends, let them do the work and warranty it.
'14 Anvil JKUR (sold the '12 at 52K miles)
'13 unlimited stripped sport (red one)
'13 JKU sport (blue one)
'10 Unlimited sport (other red one)
'08 Unlimited X (green one)
I did my own in my brother-in-law's shop. He was there to help and to double check my work. Took about 12 hours of HARD labor. Took his longest 3/4" drive ratchet with a 4' cheater to crush the crush sleeve. Holding the pinion still while pulling on the cheater was interesting to say the least. Took both of us!