1991 GMC C1500 nothing.

Well I've done all I can think of. I've got a new battery, new starter, new selenoid, new battery ends, 12 volts at the starter, ground wire is tight. Turn the key. Absolutely nothing. Not even a click. At night the headlights don't even dim like it has a load on it. I've got 12v at the starter on aux, and crank positions. Tried to start in park, and neutral. Took the dash out and seats out to get under dash to look for anything obvious wire wise. Checked every fuse I can find. I'm at my wits end. Any suggestions? I was driving it, it died. Tried to start it a few times, (and it turned over) and then this happened, and it hasn't made a click since. It's gotta be something simple, that I'm overlooking.