Help with electric on slant 6

You might want to take some effort and try to find WHY. Those rarely fail, and sometimes, the harness fails FIRST. In other words they are poor protection. some of these girls (yours might be one) get old and still wear their original factory issued link. My 67 was original.

Look for something melted, smell, etc, look for bare harnesses, and suspect the alternator / alternator area.

Did you accidently "spark" anything, or maybe connec a charger or jumper cables backwards?