Headlight switch - 75 Duster - Stumped...

2 separate power supplies instead of a jumper B1->B2, So you could have a catastrophic failure in all the smaller lights and retain the headlights, or vice versa. Smart.
Completely separate circuits/bulbs for brake and rear turn ( turn signal switch cannot interrupt brake lamps ) is smart also. This is very common in newer vehicles but quite rare for the classics.
Anyway... happy motoring.