67 Barracuda Heavy Electric Load

You mean there are people out there ignorant enough to wire in a winch, snow plow or other high amp draw THROUGH the factory amp gauge wiring? Even "I" would wire something like that in COMPLETELY SEPARATE from the rest of the system.
"Through the ammeter" is not how they are wired, but they put so much load on the charging system that they damage the charge wire, bulkhead connector, and ammeter--just like on A bodies and just like we are talking here (likely). I've said before, my old 70 RR ate the bulkhead connector and damaged the ammeter way back i the early 70's. And it didn't have a winch, lolol