Vibration & Rattle from clutch...when coasting above 60 MPH

I've searched, but I didn't see anyone describe this yet and I have no idea what it is.

It happens after giving the car gass in 4th and 5th gear...then, after letting off the gas, while coasting above 50 to 65 mph...I hear a rattle/vibration/metalic or aluminum-shaking thing...near the clucth/gear box. When I coast...and press in the clutch..the noise goes away. Let the clutch out..still coasting around 55 mph or higher..the noice somes back.

Can anyone figure this out? Me worry a bit about this one..

I put Kartboy bushings in a fw weeks ago...could it be those bushings?

Maybe you should check the Kartboy bushing, just to make sure the bolt is tight. Other then that you should take it to the dealer.
Could be your 4th & 5th synchronizers. Take it in soon.....