Headlight switch - 75 Duster - Stumped...

OK look in the factory service manual. You are going to have to buy one, used, repop, on CD, etc. The latest one you can download for free on MyMopar is a 73. There are differences, but that part of the circuit may be the same

I can tell you that ONLY the headlights is fed UNFUSED from the ammeter circuit, and there's a breaker on/ in the light switch itself

The other circuits are all fed off a fuse in the panel

The dimmer controlled dash lights are a trick. They RECEIVE power from the B2 circuit at the switch, through the dimmer control, and out TO the fuse box and TO the inst fuse and then off to the various dash lights