Originally Posted by timr
Anything is possible, but I would expect it's more likely caused by a tire/wheel being out of balance or out of round. Less likely could be part of the drivetrain out of balance.
Every vehicle, including every one I've owned, has a suspension natural frequency that is reached at some speed -- and in the range of 75 MPH is fairly common.
If my tires are not perfectly balanced, my van will start a little vibration just above 70 MPH, peaking at 74~75 MPH. If I push beyond the natural frequency and get close to 80 MPH, the vibration stops. And that's expected.
I'm not suggesting you drive even faster, but if it went away or reduced significantly, then it's a good indication of something being out of balance or out of round.
By the way, I'd check the tires carefully. I once had a tire that was about to fail where I could feel a bump developing before I could see it. I run my hands over the tire feeling for any lumps. That can cause vibration because it's both out of round and out of balance.