360 engine vibration at ~3000rpm

Wyrmrider,
Understood but there U-bolts have already been tightened and fixed the problem.(Double nutting them is a good idea.)
Jay27,
Have not tried to simply remove the alternator/fan belt. (car has manual steering, so I only have a single belt.) Car has a factory style clutch fan that work very well/smooth (had it checked out just after buying the car). Engine runs cool year round with this fan using a stock radiator and an external trans cooler.
THX-Scott