The prize goes to those who urged me to check the u-joints. It turns out it's a little bit of everything. The front most u-joint was in active decline, slapping back and forth maybe 15 degrees back and forth. Ready to fail. Glad we spotted it. I noticed the carrier bearing was clunky too. Once off, I realized the bearing is rotating OK, but the mount was loose, even though the bolts were tight. I attribute this to the rubber mount around the bearing shrinking. I decided to not bother trying to shim and replace it instead. I have a new one on the way from an eBay seller in GA, along with a bearing separator kit ordered from Amazon (I never heard of one before last night, only bearing pullers). While staring at the front assembly, I decided to replace all the u-joints, not just the one that is clearly bad. The mid and front rear joint seemed OK when I pulled them, but there is no reason to re-use them when I have good Spicer replacements in hand.
Incidentally, for anyone looking, Hummer Knowledge Base reveals the u-joint is a Spicer 5-213X. It is available fairly widely, though I found less common at typical auto parts stores when searching. NAPA has them at a decent price, but I was surprised to see them on Amazon Prime of all places at less than $20 each. I bought 4, one-day shipping included free, thinking I only for sure needed one. I'll finish the front propellor shaft and make a mental note to buy a few more to do the u-joints on the rear next time I'm under the backside for another reason. They are tight still, but just as old I'm sure. Tip: wire brush and wipe clean the yokes before trying to reinstall new u-joints, so debris isn't being splashed over everything while getting the new joints in.
Incidentally, the TM didn't give me a lot of help on how to remove the front propellor shaft, so here's how I did it for those interested: loosen and remove front and rear u-joints bolts and straps and unbolt the carrier bearing. Then, unbolt the steering sway bar and rotate it as far downward as possible. You can then remove the front propellor shaft OVER the sway bar straight outta the front of the vehicle. I couldn't find any way to remove the shaft by bending it at the center joint and going under the sway bar, but once the sway bar was unbolted and rotated down I could pull the whole mess straight forward. Going back in will be annoying in the reverse direction, but should be totally do-able.
Bulldogger
