1972 Mustang electrical gremlins

Since we bought the car last year, the radio has been intermittent, and I thought the radio itself had a short/bad ground, etc.

Once in a while, the alternator light will come on while the car is running - usually at slow speeds or idling.

The other night we had it out and after approx 1.5 hr ride, the headlights went out. I pushed the switch to off, then back on and they came right back on. It happened again - and they came right back on by turning them off and back on.

That happened just as we were getting home, so don't know how long it would have persisted.

I can turn a pretty good wrench, but not real good at chasing electrical problems.

I'm guessing it's a bad ground somewhere - is that a good assumption?

I guess I'll start with the chassis and battery ground, and then look over the alternator, belt and wires, and see if there's an engine ground strap.

Since the three issues (may be) related:
radio, alternator light, headlights...
where else do I look, and what's the process?

Thanks!