1995 GMC Safari Head lights or Head light Switch

Usually the headlamps use a circuit breaker, part of the headlamp switch. Other circuits that receive feed from that switch are fused. I'd have to check the wiring circuits. Check the wire/s at the lamp socket, for high beam, lite green wire is voltage, black wire is ground. If no voltage, check the feed going to and from the head-light switch. If that checks out, you'll have to check the bright/dim switch.

what about the bulbs? what type are they? The 95 was the transitional year from plastic to glass, er the other way around. Its unheard of for ALL 4 lights to go at once, so what else could it be?

The partsbook showed a composite headlamp assembly, uses a bulb, I tried to insert a picture, it didn't work. The parts store will show you.

I think the problem is either a switch or wiring circuit, I can't tell which, without testing.