No headlights on '75 duster

OK, first, the headlight power gets to the headlight switch separate from park/ tail, which comes from the tail fuse

Headlight power goes to the light switch from what is known as the "in harness splice" or "no1 splice" which is a permanent splice on the black ammeter wire under the dash and taped into the harness

The light switch has it's own breaker.

But check the "easy to get at" first

Easiest is the dimmer switch. With the headlight switch ON, TWO of the dimmer switch terminals should be hot, and when you switch from hi to lo or vice versa, the the dead terminal should become hot, and drop off one of the other two. The dimmer has power coming IN to one terminal, and power going OUT one one at a time of the remaining two

From there the high and low beam power goes through the bulkhead connector, and out to the lighting harness.

What do you have for a shop manual/ wiring diagrams?