I have discussed the cause and solution to this problem with the manufacturer of aftermarket Mopar harnesses.

According to them, the original design of the bulkhead Packard Series 56(?) male and female connectors is limited to around 38 amps. While this is fine for turn signal lamps and coolant sending units, it strains the design limits of the connectors--under optimal conditions including brand new wiring and 40 amp alternators --to carry the entire charging circuit's load through these connectors (not once but twice!) through the bulkhead connectors. Add 40 odd years worth of connector corrosion, higher current demands for aftermarket accessories, and higher output alternators, and the end result is the problem you and so many other Mopar enthusiasts have experienced.

If it makes you feel any better, I replaced ALL the wiring harnesses on my Mopar with brand new repops and STILL had the problem reoccur.

That's when I went to the manufacturer. Their solution was to add a parallel fusable link wire from the batt post to an up-gauged red wire going to the firewall, where they split that wire into two pairs of terminals at the firewall, then back to one up-gauged red wire to the battery side amp gauge post. (Same treatment for the black wire to the No. 1 splice and alternator, except that there is a single ring terminal on the alternator post.)

This design modification allows the bulkhead connectors to still be unplugged. (Unlike the alternative to pass an unbroken wire through the drilled out cavity.) The two extra cavities that are taken up by this modification require that two low-yield wires be ousted from each of the front light harness and engine harness plugs and transferred over to the unused (for cars without air conditioning) no. 3 and 4 cavities on the neutral safety switch/reverse light harness.

So far this solution has worked for me. And I defer to the manufacturer's expertise in arriving at this solution, which, incidentally is the standard fix that they employ when asked.

Interestingly, the manufacturer did not suggest that I bypass or eliminate the alternator gauge. Assuming the terminal studs are corrosion free and carefully cleaned, by themselves, these gauges were not the weakest link on the battery and alternator feed circuits--that claim goes to the under-engineered terminals at the bulkhead connector.