Mine started rattling around 6000mi, now it sounds like a 55gal drum full of bowling balls bouncing down a set of concrete steps... at first only when the clutch was in (any speed), but lately I'm sensing vibration when I get off the gas in gear.
Something ain't right. It's going to the shop.
"If you're going to kick authority in the teeth, you might as well use both feet." - Keith Richards