My 71 chevelle has a high speed vibration that is trying to shake the fenders and hood off the car!!! Ball joints, and all front end parts are all good. New tires as well, and the wheels are not bent. The vibration is only felt at high speeds, ( 75 and higher ) If i have the rear of the car up on jackstands and run the mph up to 75, there is no vibration in the car. The driveshaft has new joints. If i run the car on jackstands at a low speed, and watch the driveshaft, it appears that it is not running true, but am told this is not uncommon and shouldn't cause a vibration. Anyone have any ideas here, short of taking it to a frontend shop and having them replace everything under the sun, only to have it stilll vibrate?
Thanks for any help that anyone can give me on this issue.

When did you get the tires? Maybe they weren't balanced properly.

I just got the tires this week, and they were spun balanced, off the car

In the old days, they balanced them on the car by pressing a motor to the wheel and mounting a balancer on the rim. It's a long shot but, if you can find someone who has one you can isolate the problem.

Chuck

If its in the front, I'd first look at the wheel bearings. Have they been packed with grease lately? I have a vibration and I reduced it about 80% by replacing my wheel bearings and hubs. It went from a teeth shattering vibe to just a slight annoyance. I'm going to go back in there and repack them to see if I can knock out the remaining vibration I still have.