Really the only 24v on your truck is the starter, and sort-of the glow plug system. There is one 24v circuit that runs into and out of the truck for the starter system, and I think that crazy round connector under that dash probably has a few 24v wires in it. Mostly, the electrical system is the same as a civy truck of that era, which was not really much into extra electrical load inside the cab...
That said, I'd keep the power under the hood, with relays to activate the lights. Pull 12v directly from batt #1, immediately fused, to relay blocks on the driver's fender. To actuate the relays, use feeds from the parking lamps and high beams, which are in the harness right there by the fender. Fore each relay, run the ground wire inside, to a switch, and ground the other terminal of the switch conveniently inside. This way, there are no high current wires inside, and minimal wiring to get it done. Your fog lights will work anytime your parking lights are on, and your driving lights will work only when your high beams are on, so if you dim your lights for an approching car, they turn off, then back on when you go back to high beams.
(Soapbox alert!!)
And finally PLEASE adjust your lights. ALL of your lights. I hate nothing more than some fool with one headlight pointed at my face, and the other off in the ditch... Same goes to fog lights... If they're shining in my face, they're doing you NO good. They should be mounted low, and aimed low to the road, to light UNDER the fog, not up into the trees... In heavy fog, rain, or snow, this reduces the amount of light that ends up reflecting back in the driver's field of vision. (This is why I tie them with parking lights... You want tail lights when using fogs, but ususlly not headlights...
(End Soapbox rant...)
C
