Factory ammeter

Bingo! It's the higher amp alternators that fry the terminals. The original alternators were 35A, and the remans put out 55A minimum. So unless you are running your original alternator your terminals are probably overworked. I know someone who replaced his alternator with a reman, and a short time later the starter began to intermittently engage while driving down the street. The bulkhead housing had melted around the charging terminal, allowing the charging terminal to intermittently contact the "start" wire terminal. I have rewired 4 67-68 barracudas and found that every one had the bulkhead connectors slightly melted at the charging terminals.
Reason for the "MAD Bypass", though that disables the dash ammeter. Some owners instead install a dash voltmeter. I added a shunt diode to my 3 1960's Mopars so that increasing currents begin flowing direct from alternator to BAT+. The ammeter is still active, but doesn't peg. My cars have the 1965 bulkhead connector with buss-bar feed-thrus for the higher ALT and BAT currents (retrofit to my 1964). Posted the details years ago.