65amp wiring/trouble shooting

If it is melted near the ammeter, that IS a huge clue. The ammeter is likely a problem. Here is the way they die

Typical Mopar alternators do NOT have the studs welded/ soldered, or sometimes not even crimped to the "guts" which is the shunt. All that current goes through there. The thing makes connection by the idea that it's all clamped together, except "it's not", sometimes. The insulating washers compress and come loose, some of these girls have plastic components of the cluster sandwiched in there, and the plastic compresses, the thing heats up because it's loose, and the heating causes it to get even more loose

You need to either fix it or bypass it. You can (if you are handy) take the ammeter apart, and silver braze the ammeter studs to the shunt. Then, you tighten the connections jam nut--to stud/ connections--to jam nut, and it will not matter if the junk in between comes loose.

IF the end terminals of the wire(s) in question look burned/ corroded/ cooked, I would cut the wire back and replace the terminal, or whatever else you need to repair it.