Here are some photos I took of my 1970 GT dash loom and gauges before I installed them in the car. The car it came from was not equipped with a rear defrost, fog lights, or AC. The red wire that goes to the gauges and switches is constant power, black and red is switched +, black-yellow is for the turn signal circuit, grey is illumination, and blue, blue-black, blue-green, are signal wires, i.e. a ground whose resistance varies. Brown with no stripe is always a ground. Blue-white is D+, green to tach is pulsed DC from - of the the coil. I'll have to cover ammeter and fuse box wiring in a separate post as I do not have a wiring schematic handy. The larger gauge wires from the switches are for the blower, parking lights, wipers, etc.