My truck had a vibe that drove me AND my mechanic nuts. He started dismissing my bitching about it. THEN I took my truck down to his shop, jacked up the rear, took the tires off started it up and ran through the gears while he looked underneath. (I removed the tires to eliminate them as a source of the vibration.) Turns out it was the trans output bushing. They screwed up the installation. VINDICATION.
