on an 08 he should have a Delphi box(rusty box with Delphi on the bottom vs. the newer all black chinese boxes). Fully rebuildable.
Look at PSC for rebuild kits(I know they sell new sector shafts) or call the guys at West Texas OffRoad and I bet they will sell you a rebuild kit.
I would put a sector shaft brace in when you put the box back in. The problem with the boxes is sector shaft deflection from trying to turn big tires, the deflection then tears up the seals and eventually the bearings and can also bend and crack the actual sector shaft. A brace holds the sector shaft on a second set of bearings outside the box turning it into double shear. $100 will get you a good sector shaft brace, but you MAY run into track bar clearance issues.