Good point on balance Bill.
My uncle Bill had a near new shop van that one day seemingly picked up a bad vibration at 65 or faster. The dealership had looked it over a number of times, wheels, driveshaft, etc. with no luck. Then, after more carping, Dodge sent out a factory rep to look it over. Next day, Bill got the call to come and pick it up. He and the tech hit the highway and all was fine. Back at the dealership, the rep. showed Bill out back in the parts department what it was.
A tiny dent on one side of the very long aluminum driveshaft! Apparently, the local quick oil change shop used a side lift hoist and the lift arms pinched the shaft just a tad. Btw, Bill was amazed such a tiny dent could throw off the balance so much.