Ground wires

Some grounds are thru the case of a component, which can be a problem. As mentioned, don't rely on a sheet metal screw to ground the electronic ignition module or the voltage regulator. The factory did that, but it causes many problems 40 yrs later. I once had a "bad" alternator in my 69 Dart, but a rebuilt one didn't fix it. Ran a jumper from the alternator case to BATT- and it started working, so I removed it and sanded the case and bracket contacts. Worked fine after that and I returned the rebuilt one, since I swapped it right there in the parking lot.