I have found that the clips that hold the caps on the rear u-joint have eaten into the pinion yoke allowing the u-joint to move back and forth in the yoke. In other words, the driveshaft does not stay centered in the rear yoke anymore which causes varying degrees of vibration at highway speeds as it moves around. The straps are tight. Has anyone else had this happen before? The car has seen alot of drag strip use but I've never heard of this before. What yoke upgrades are available or should stock normally be fine?