The rear windows leak, one u-joint at 34,000 miles.
The Avalanche is a very nice truck. The 5.3L is very powerful and the truck tows very nice. We had a 1998 Chevrolet Tahoe before this and the ride is MUCH better. The back window leaks and we had to silicone it in to stop it. The seats are very comfortable and the back seat has ample space for taller persons. The armrests are a nice feature that I would not go without. I also had the Chevy symbol replaced with a billet one because it was warping and very ugly.
BTW- Dad fixed this problem. The right rear had a small defect, he sprayed rubberized undercoating on the seam where the 2 halfs of the undercoating come together...