What kind of noise is it/what does it sound like/can you describe it better?
Idling louder when the clutch is depressed is a little mysterious, unless it is a loud bearing noise from the release bearing or something. How good are your engine mounts?
I found with my BJ42 that there were a hundred things loose around the engine compartment, including the hood, probably from years of diesel vibration. If you systematically tighten everthing the truck will become MUCH quieter. However, none of these noises was connected to clutch in my case of course....
B