73 Duster crank but no start / blowing in-line fuse on red ignition wire

Hey, 67dart.. thanks SO much for the info and the diagram. I saw some of your explanations on other posts as well. This was super helpful!

We tracked the issue down, and now I have a couple questions. The issue is with the alternator. We unhooked it completely and got the car to run off the battery without smoking any wires and without blowing the fuse.

I don’t know if you can see in the pictures I posted, but is this style that was installed the wrong one? We are wondering if this one either failed, or if it needs to be internally regulated or not. Any insights are much appreciated. Thanks again!
I missed something, do not see an alternator. Should have the later 70/ later style with the flat electronic regulator. You can check quick if it is locked into charge by watching the ammeter, with it charging. Disconnect the green wire at the alternator and see if it quits charging.

I still don't know what that fuse does. Does that fuse kill the headlights as well? Hard to say