Brake Light problem

[KW900L]

I have a 1994 GMC K1500 Z71 with A 5.7L,a/t,p/s and 4wd.The problem I'm having is the brake light fuse is blowing whenever I step on the brake pedal.I have replaced the turn signal switch,brake switch, master cylinder and the tail light "boards".I have traced wires up and down the frame, rear end and under the dash.I have even tore down the steering column tracing wires in there.I have checked the wiring for the third brake lght on the top of the cab.I have turn signals and up until recently hazards.I am stumped,any advice you can give will be greatly appreciated.Thanks for your time and expertise.

[GM-Tech]

The only advice I have is to start disconnecting things, cutting wires if necessary, to try to narrow it down.