OK, I have a 74 Duster with 318, non AC. My negative cable from the battery appears to have a fusible link, split off from the main negative cable to the block, going from the battery terminal to the radiator support, the mounting point is shared with a another ground from what looks like a wire from the headlight wire harness. So, the fusible link broke down and melted. Once this connection was lost I lost all power. We reconnected the wire and found power came back and there are no problems with turning on lights, horn etc. The problem begins once you crank the engine over. Since the coating has melted off the wire you can see it and when you crank the engine it turns orange (hot). Now before you respond and say "you have a short", I get that. Is there a common problem that occurs with these things that could give me a good starting point? I may be able to provide some key information that I may have missed, let me know, thanks.
