Hey guys, I too am highly annoyed with the vibrations in my truck and have been scouring the web looking for answers. Sadly I don't know the cause of these high speed vibrations but I saw something today that caught my eye. I'm driving my girls chevy cruise (low vantage point) going about 75-80mph and I'm driving alongside a 2014 or 2015 CC Silverado Z71 (stock wheels and tires). I look over at the rear wheel and that son of a bitch was oscillating laterally (front to back). Bad enough for me to see it with the naked eye. I immediately look at his front wheel to make sure I wasn't seeing things and the front wheel was spinning normal in place. I would estimate that the oscillation was about an inch or so in either direction. I don't know if this is a result of faulty leaf springs or what. but maybe me saying something will trigger you guys to have your trucks looked at from another vehicle, at speed, to see if this is a common occurrence with everyone that has vibration issues. Then maybe a solution can be figured out for this stupid issue.
My main vibration complaint is at 30mph. for whatever reason my truck shakes in between 25-30mph ONLY on acceleration.
Any help on that would be greatly appreciated lol