The headlight switch on the ’37 Ford is attached to the bottom of the steering column – a unique switch that turns power on & off and runs lights, low beam & high beam when the lever on the steering wheel is moved. A long rod runs from that lever down through the middle of the steering column to the switch. The wires are factory “soldered” into the switch & run to the lights.  If the insulation is gone from the wires inside the switch (and it probably is), when the switch is turned the fuse will blow because the bare wires are grounding.