Well i test drove a 2014 Denali 4wd crew cab short box w/ 5.3L just for shits and giggles... took it on the high way and i had it at 75mph for about 5 minutes with the cruise on....... no obvious shakes or vibration.. truck rode quite good. It had around 25k miles... i'd pick it up but why the heck would i get a denali without the 6.2 engine. Anyways, i plan on test driving more to find this infamous vibraition.