I have a 1984 6.2 that has vibration in the engine at the same RPM no matter what gear it is in, even nuteral. I have notice that at idle, now, that it has a very fast vibration(like a electric sander).

Does anyone have any idea what this may becaused by?

:help:

Check your harmonic balancer for rubber failure. Remove all of your belts and run engine for short amount of time, is vibration still there? Vibration could be coming from an accessory. If this doesn't do the trick, pull inspection cover from transmission and inspect torque converter bolts. Look for cracks in flex plate.:grd:

I had the same problem but it got worse really fast. I'm not disagreeing with the harmonic balancer or accessory, i would check your u-joints andtires, but it could be a loose belt too.