The emergency brake on the '73's been acting up, so since I've got the car up on jack-stands right now for suspension work I checked things out. Seems the cable has been rubbing up against the rear edge of the muffler, and over time frayed almost through. Annoying, but at least I found it before it snapped completely.
Now, in addition to the shocks and other work I need to see if I can move the muffler 1/2" further to the rear. Sigh....