main fuse

Here you go
Standard wiring.

And this thread has a couple of posts (one by me one by 67Dart273) that explain it.
https://www.forabodiesonly.com/mopar/threads/1973-duster-electrical-issue.543142/post-1974343881
Aother example of troubleshooting
https://www.forabodiesonly.com/mopar/threads/burnt-some-spaghetti.540122/post-1974292029