UCAs are known for failure in the gm trucks that go higher than 2” but as stated the op has aftermarket ones installed. Seems there’s not many reports of failed ucas on these new suvs maybe because lifts over 2” weren’t very common until more recently
One of the Youtube reviews of the Escalade V interviews a GM engineer or product manager who states the Trail Boss CV shafts were one of the few driveline upgrades made for the additional power. I don't recall which channel.
I wonder if that and the uca swap would be enough to bulletproof against mechanical failure due to lifting. We bought a Z71 Suburban last May and after an unpleasant experience with some mud that my old 4Runner would have just walked through I mentioned to my service advisor that I was looking at lift kits and mud/hybrid at tires. He informed me that they're seeing a lot of trucks coming back with damaged suspension and broken axles caused by guys running tires too large and needlessly high lifts. Personally I haven't seen anybody running around with a 12" Skyjacker kit and 52s so I'm assuming he was talking about 3-4" kits and guys running 37s which is what I had in mind before our conversation.