I have 2016 Silverado 1500 crew cab LT Z71. It vibrates intermitantly, I can go down the interstate 74 mph and it will ride smooth as silk then 2 seconds later it will start shaking and do that for a couple of miles, then smooth out. About a month ago I had a load in the bed of the truck maybe 250 lbs and drove on the interstate at 74 mph for about 110 miles and never shook at all. I've been following this since mine started doing this and wish someone would come up with a fix for this.