Long story short, I bought a brand new 18 last September and it was bought back after spending 4 months at the dealership with a problem they couldn't diagnose. It would shake violently with a trailer hooked to it. After receiving a replacement it vibrated so bad that the dash shook. The same dealer told me it was a "normal characteristic" and talked to me like i was a complete idiot. That was the final straw. Drove it directly to GMC and they hooked me up with a decent deal and the incentives negated the negative equity. Much better truck for the same money. Smoother transmission, smoother ride and comparable power. I miss the immediate power from the turbos but comfort makes it work out just fine.