ok so I've been making some headway on the rewire and hopefully with some help I will have the truck powered back up tonight. I started out soldering connections, but my HF soldering gun didn't like me, so I'm making solid solderless connections with heat shrink over them. headlights and taillights are hooked up, and so are the majority of the underdash connections, just have the headlight(partway done) and wiper switches, alternator, starter, fuel gauge, and lots of grounds

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A question though:
I was looking at the headlight relay mod diagram, and was wondering, is it possible to run only one power wire to the relays from the battery or do they need to be separate?
also, I was going to just put the relays inline, mounted high up on the drivers side fender(ok spot?). use the wires coming from the switch for triggers, and the headlight wires that are part of the harness. am i required to use 12 gauge wire instead? I'm trying to keep this simple, but i don't want to fry something if it's gonna be too much juice for the smaller stock wire.
overall though, this has been much more straightforward than i first thought, and i don't hate wiring as much now haha.