IMO...half-shafts are consumable parts. Think of them as brake pads. Keep a fresh pair on the shelf and get in the habit of swapping them every 60K miles or so. Even sooner if you rip a CV-boot. This applies to ANY IFS rig. Its just part of playing the game. Always replace them in pairs...the failure rates on CV-joints are so predictable that it doesn't make sense to replace just one side, unless its very early in its lifespan. Soon as you get one side done...the other will blow within a month or two. Hopefully your dealer will do both sides and replace the axle seals too. This is a common leak spot, and for the extra $10...they might as well replace them while they have the shafts pulled.
Technically the dealer has no obligation to replace both sides but, back when GM was worth a crap...this was standard practice. These days there is no consistency and even less credibility among GM service centers...so you sort of "get what they give you". I've heard stories of H3's going in for a simple seal replacement...and coming out with a new steering rack, tie-rods, and two new half-shafts & seals. But that's probably not gonna happen. Fortunately on the H3...all of this stuff is very easy to change, and anybody that off-roads one should get familiar with the job. All you need is basic hand tools, a large socket for the hub, and of course...a big hammer.
One last thing to note: Don't screw around with disassembling a shaft to replace a CV-joint. There are vehicles where this is cost effective but, on the H3...the quality of the part is simply not worth the hassle. Instead, just do a core-exchange on the entire shaft and get some fresh NAPA or Cardone shafts, for about $100 per side. Put em in...blow em up...repeat as necessary. Remember...treat em like brake pads.
