Help! vibration problem!!

[skiwesser]

Ok, I've got a slight vibration somewhere that occurs in any gear

at between 2200-3000 RPM. It is loudest in 4th but you can hear

it in 3rd & 5th, you can also hear it in nuetral upon deceleration,

only for a few seconds (when whatever is wrong is at proper rpm?)
My T-5 doesn't have many miles on it and is smooth as silk, rear end set up by a great meachanic (not long ago), U-joints are OK, so i doubt those as culprits?

Also it doesn't do it setting still in neutral i.e not in motor right?

any help appreciated!!!!