If noise is easy to duplicate, find a safe place you can coast with engine off. Roll with transmission in gear, clutch depressed. Release bearing will not be rotating but input shaft will rotate in pilot bushing.
I followed this suggestion and it turned out to be very helpful. The noise was barely happening and intermittent just driving the truck but when I did as suggested, engine off coasting in gear with the clutch depressed the noise occurs full time. There is also a slight vibration felt thru the clutch pedal any time the noise occurs as well which made me think it was the throwout bearing. So my problem is most likely the pilot bushing. Too bad I don't have a leaking rear main seal, maybe that would keep it quiet. Just to be sure, if the input shaft bearing in the trans was bad the noise would be there all the time wouldn't it?
