UPDATE:

So I got the A/C working, and the headlights working, but not at the same time. I did this by moving one of the jumper wires to a different headlamp relay pin (I can't remember which one). But, when the vehicle is in park and I turn on the headlights, the A/C stops working. Headlights off, A/C works again. Until I drive. The moment I put it in drive, the headlights still work but not the A/C.

Also, when I turn the truck on, let it run a moment, then turn it off, the fuel pump is still running. It's never done that before.

It's almost like there's a current draw from the transmission that's pulling all the power. Is this possible? Or could it be inside the fuse box itself? Is it possible for the fuse box to go bad?

 

PARTLY FIXED. Turns out there was a completely bare wire under the dash that I hadn't seen before. Fixed that, fixed most of the problem. Found a spot where the insulation had worn off a green/white wire, fixed that.

Now everything works except the 4wd. It's blowing the 10A ATC fuse every time I try to shift the transfer case.