Put it up on 4 jack stands and have some one run the throttle to get it up to 60 MPH in high gear at light throttle pressure and see if you can see any run out on any of the parts, drive shaft, wheels or tires out of round scope
Let us know what you find, mate grin

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)