You'll also want to determine whether you have a small-bearing (2.834") or big-bearing (3.150") housing since that will need to be specified when ordering new shafts. You may not see any need for 31-splines now, but it sure would be cheap insurance since you're swapping shafts at this point anyhow...but it sort of depends on what carrier you have. If it's open, new side gears and you're good to go. If it's a Trac-Loc, you may need a new carrier. Someone at Randy's R&P, Currie Enterprises, Moser, Dutchman, etc should be able to answer that more definitively for you.
If you have a big-bearing housing, you then should have the choice between sealed ball-bearings and the heavier-duty, SET20, tapered roller bearings. Either bearing should be fine for what you're doing, but keep in mind that the SET20's need to be lubed with the gear oil and as such no inner oil seal should be used. The seal with the SET20s is captured on the shaft by the bearing.
Yukons run about $219.00/set complete with ball-bearings and retainers last time I shopped for them for my Bronco at
http://completeoffroad.com/c-59879-ford-9.html. Granted, you'll need the GM pattern and register, but that should at least give you an idea.
HTH,
Tobin
KORE3