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It could be the "RED" feedthrough terminal for the fuse link on the road to the ammeter
But you are right about one thing........a fire is never good. Maybe the short was bad enough it burned one of the feedthrough terminals. Only way to find out is to start with a diagram and trace it out.
"The MAD article"
Even if you don't do this mod, this is a great simplified diagram of how the main power distribution works:
Catalog
View attachment 1715193555
"Just follow the map" The main power comes from the BATTERY---to STARTER RELAY STUD----THROUGH FUSE LINK---------THROUGH BULKHEAD CONNECTOR------TO AMMETER-------OUT AMMETER ON BLACK------TO WELDED SPLICE
From the splice the thing branches off several ways. The splice is in the black ammeter wire up in the under dash harness. Feeds off to headlights, fuse panel "hot" buss, feeds the ignition switch, and branches off back out through the BULKHEAD CONNECTOR to the alternator
