If you're just leaving the gearing as it is and replacing only the differential, then you'll need only a selection of carier bearing shims. Measure the backlash before disassembly; you have to pull the carrier bearings to get to the shims. Start with the stock shim set up, and re-install then remeasure backlash. If you get lucky (we did) the backlash will be right back where it started and you're done. If you're not lucky, you'll have to pull it back out (likely a case spreader will be required as it will go in MUCH tighter than the original came out) pull the bearings again and alter the shims to get the backlash right. I put new carrier bearings on mine too.

Process is MUCH more complex if you pull the pinion - bearings, races, setting pinion depth and pre-load, crush sleeves - yuck.