Need help figuring out my electrical problem

[DannyJ67]

I have a 67 truck with some kind of crazy electical problem I cannot figure out. It started a few months ago when my truck died while driving with both my headlights and my windsheild wipers going (in the middle of a thunderstorm.) My battery would drain everytime I parked my truck unless I unhooked the battery. After searching for any kind of short or touching wire I found that one of the wires that goes into the connector to my ignition switch was melted (The exact wire is label as 20T on my wiring diagram) so I replaced the connector and the entire wire. Now it won't even turn over. Also my lights will not come on either. I have checked and rechecked my work and It all appears to be done correctly according to my diagram. HELP PLEASE!

[VetteVet]

From what I can tell by your post your shorting problem is with the fuel gauge wire that goes to the instrument cluster or the brake warning light wire that comes from the sensor on the prop valve at the master cylinder and goes to the instrument cluster.
Both of these wires are connected to ground through either the brake sensor or the fuel tank sender. At some point one of them has touched a hot wire and burned the insulation off the 20 gauge tan wire at the ignition switch. Were you able to tell which wire was burnt?

There is a red wire that goes into the firewall block that feeds the fuse panel and the headlight switch and the horn relay. If you have no power to the inside of the cab and the lights won't work or the starter or anything else then it's possible that the fusible link in this red wire is burned into. This link is located a few inches from the battery positive terminal and runs to the terminal on the right hand fender just aft of the battery. Take the positive battery cable end off the battery and check for continuity between it and the fender terminal. If you have an ohmmeter it is easy. If there is no continuity then the link is burned out and you will need to replace it and also you will need to find out if you still have the short to ground before you replace it or it will burn out the wires again and probably burn out itself.
Check out the red wire first and post back then we can get into the other circuits.VV

[DannyJ67]

Ok so I tried out everything you told me to do and problem seems to have been solved. Wow I spent forever trying to fix it. THANK YOU MUCH.