it wouldn't be the 1,2,3,4th G80 I have taken out of service before
My Envoy had the G80, but in an 8" rear, and when I had a similar issue it was replicated from a stop while already being in a small turn. I was on an off ramp, on a hill, turning to the left. Once I started up again, I would get a small "bump" in the rear and it wouldn't do it going straight, only applying a good load from a stop while turning, couldn't figure out what it was.
I ended up with a chipped spider gear and I just swapped the axle for a SS 9.5" as I have the 4:10 anyway.
I'm sure the few rainy exits from a parking lot lighting up a tire then the G80 locking contributed, and this was before I was aware of their delicate nature.