Ford 460 Engine vibration in overdrive

If your drive shaft has a slip joint, check that also. If too full of grease it cause issue like you are having. release the pressure on the grease zerk till no grease comes out. Slip joints do wear out. Did you do the u-joints or have them done. Have you check to ensure they are not binding. I know you stated you had new ones installed.

Also as Lou state the pinion angle. A off angle will kill u-joints.