Please add me to the list of shakers. Same issue as all of the rest. Very disappointed in GM. Bought truck new in January. 53K sticker truck, rides like a farm wagon. Been in for service twice. Noticed the vibration on the test drive and told it was flat spots on tires. Will never buy GM again. Have been a loyal customer for 15 years. Sad a company will not own up to an engineering flaw and fix it. I feel that after being lied to on the test drive, there should be a buyback of the vehicle. I am letting everyone I know to stay away from GM/Chevy.