Strange Clutch noise on 03 GT

I've got a racket in my 02 GT but I'm not sure it's the same thing you hear. In my car, it's most noticable cold. With the clutch pedal down and the trans in gear I get this "cylical rattling" noise that I can "feel" in the shifter. If I put the trans in neutral and release the clutch, the noise goes away. When the clutch is depressed again, the noise will return, quicker if the trans is slipped into gear.

At first I thought it might have been a crank thrust bearing (loading it with the clutch trying to push the crank out the front of the engine) but I'm increasingly thinking it's the clutch disc "battering' around between the flywheel and pressure plate and the gears in the transmission knocking against one another as a result. When I kneel down beside the car the noise definitely seems to come from the trans/bellhousing area.

I recently had the TR-3650 TSB work done and they (Ford dealer) assured me the release bearing was fine so I don't think it's that.

When you say the noise is there "only when clutch is engaged", you mean the pedal is completely released, right? If so, it's probably nothing to worry about. Might just be the release bearing and release arm "chirping" a bit as a result of some runout in the pressure plate diaphram. If you touch the clutch pedal (press it down, say, 1/2-inch or so) does the noise change or go away? If so, it's probably nothing to worry about. If the noise was a squeal or rumble with the pedal on the floor I'd suggest the release bearing was smoked.