Technical Wire new stop lamp

can anyone decipher the wires coming out of the firewall blocks on a f100, i bought a laminated wiring diagram but around 60% of the colors are different to mine.
I am trying to wire up a stop lamp switch but cant seem to find the correct wires!!

 

If there is power to one of those wires that are close to the switch , it don't matter which one goes to which terminal. If those are the light wires , just tag them together to see if the lights work.

 

Not sure what is behind the piece of plywood, but that bothers me.

 

I think that is the master cylinder adapter? I wouldn't trust my life or anyone else's to that! If you make a panic stop and the master cylinder separates from the firewall your brake lights (and brakes) wont work. That needs to be fixed immediately.
I'm not trying to be a smart ass, but you may want to think seriously about doing some major rewiring. A new harness may be the best way to go with all the questionable stuff just in those pictures.

 

Not much of this makes sense. QUOTE; " . all the lights and indicators work but no matter how i configure the live to the wires "i think are the right ones" i can get brake lights. the prevous guy done a lot of chopping to run a modern style alternator" end of quote.

You are aware that the Brake lights go through the Turn Signal switch,, Right? So if the signal switch is as nice as the rest of the wire we see the issue may not be the actual Brake Light Switch.
The Wizzard

 

i can get brake lights. should have read CANT get brake lights!
Ive sorted it now, the original wire had a brak in it, as it was brittle and must have broke when being moved about.

 

Are you trying to hook up to that pressure switch in your proportioning valve in the first picture? Most proportioning valve ports for switches run a dash light to warn of low brake pressure, not a brake tail light switch.