Jack speaks the truth! If you have the effort reduction kit (standard issue starting in late 1972), it's quite possible the sound you are hearing is the assembly eating itself.
There will be a tech article in next month's PCNC newsletter showing what can happen if you let things go too far for too long. A poor fellow in San Diego really destroyed his linkage, and the clutch stopped working completely. It's easy to fix (by replacing the worn-out parts) but the real solution is to lubricate everything thoroughly.
Here is what the system looks like. This is with the whole pedal box out of the car; the view is from the center of the car, looking to the side. Get in there and lube everything and hope for the best!
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