All,
GM was great. They agreed to do a $5,000 trade in allowance on my 2015 Silverado 5.3 DoubleCab 4X4 LTZ. The truck had 4,000 miles on it and the vibration was unbelievable. It would make my wife car sick. I had to drive 6, yes 6, 2016s before we found one without a vibration. I ended up "eating" $7,000 to get into a 2016 but I felt it was worth it because I had a $48 (sticker price, not what I paid) truck that my wife couldn't drive in. 40 miles on the truck and it has the same nasty vibration from 70MPH and up.
All the dealer wanted to do, was keep road-force balancing the tires. I thought it was ridiculous. Rather than wait weeks for an appointment, I paid $2600 for new aftermarket rims and tires and I'm stuck with the exact same vibration. I am now $10k into this mess. Do yourselves a favor and warn people.
I have started this website as an attempt to protect others from buying a Silverado. It will take a couple of days before it is up.
www.dontbuyasilverado.com