Shaking around 70MPH
When I'm going down the highway around 70mph, my truck gets a terrible shake going. It feels like it's just being constantly bounced up and down, and is noticeable. Sometimes it even makes it a bit hard to breath.
The steering wheel doesn't shake at all, and it drives straight. I just had the front end alignment done, the tires are near new, and the rear rotars are new.
Sometimes it won't do it for a few miles, then it will be bouncing for a few miles, and go back and forth for the whole trip, no matter what the road conditions are.
Any idea of what this could be?