Stewart,
Everything screams throwout bearing, but your math says otherwise. If the engine is relatively new, and so is the throwout bearing, one would be inclined to look at the '42 transmission as the noisy culprit. This might be true, but it would certainly make noise when the clutch was engaged and the guts and bearings of the transmission were spinning...not when it 'wasn't' spinning, as in clutch released.
As creepy as it sounds, I would be inclined to stick the truck up on jack stands, pull the gravel pan and watch and listen (a hose or stethoscope) while the truck ran, and someone did the clutch drill.
The problem is the reverse of what would be expected in a normal failure. Maybe someone will pop in with a "been there, done that" solution.
Could any clutch linkage be hitting a tailpipe or something else when depressed that gives you the false impression it's the bearing.
Stuart
