As the supercharger is the most likely suspect, I'm moving this to Forced Induction...
Now, do two things:
1: grab the serpentine belt (with the engine off
) can you move the belt so that the pulleys rotate some? That would point towards the harmonic balancer
2: take the SC belt off and turn the pulley by hand both ways, and try to move it left/right up/down and see if it has any play in any direction you can get it to move. Rotational play points to the nose drive coupler.
The coupler itself isn't too bad to do. Since you have a Series II, you can remove just the nosedrive. A lot of people (like myself) prefer to do the nose bearings at the same time. I recently did bearings and coupler with great results in the noise department. For more specific instructions look for willwren'* ULTIMATE GUIDE TO REBUILDING SUPERCHARGERS. You'll be able to find a link somewhere around here.