1974 Dart 2nd fuse blowout

Fetch fire extinguisher. Keep it close.

Disconnect everything in the circuit.
Install new fuse. It should not pop.

Plug in each thing. When it pops, bobs your uncle. If it pops with everything unplugged, the issue is in the harness.

On my car, the brake wire was melted to another wire inside the taped up harness, and new fuses simply resulted in smoke blowing from dash vents.

I'll wager there is a melted connector at the bulkhead no matter what.