Bought new, Loved everything, wanted to keep until wheels fell off. Then, the rear-end fell out of my dream! At 96,000 rear-end had to be rebuilt. 38,000 later, pulling a 12 ft trailer, rear-end went out again. Replaced with a rebuilt one. Just a few thousand miles & I can hear the familiar hum again. Many Avalanches must not have this problem, but if you got one with a faulty rear-end, it must be faulty from the factory, and can't be corrected. I'm now figuring, any rebuilt you buy is one of the faulty ones that can't be really fixed. So I guess I'm in a fix, unless I get one off a wrecked truck & pray it's from a truck with a good rear-end. But this is spending around $1100 to $1400 everytime.
Please do your research, before you buy an Avalanche. Consumer Reports rates all years, but 2012, as worse/much worse than average. We bought our LTZ new in 2007 and currently have 97,000 miles on it. I was pulling my camper home last year, from a camping trip, when, about 6 hours from home, the transmission failed (87,000 miles on the vehicle). Fortunately, I found a Chevy dealer close by and they were amazing (wish they were closer to home!). I've had most all of the problems that Consumer Reports and owner reviews have detailed. Power steering pump replaced; starter replaced; routinely replace TPMS sensors; back-up lights stay on sometimes, running battery down; currently having intermittent problems with the all-wheel drive, stability control, and traction control systems (don't know what's going on there); and myriad of electrical problems. I contacted Chevrolet's Customer Assistance Center and got the standard response that it's probably abuse and poor maintenance, completely discounting Consumer Reports' and owners' reviews. My local mechanic, I refuse to go to a Chevy dealer - don't trust them, suggests that I unload the Avalanche before anything else major happens. This is really sad, since I love the vehicle and hate to part with it. Like another reviewed said, it's truly a love/hate relationship.
Update 9/20/2016 - Got rid of this headache in March. Bought a new GMC Acadia and love it. It tows my camper better than the Avalanche and it's only a six cylinder. Hope it gives me better service! I bought a 10-year, 100,000-mile extended warranty, just in case!