[Dave at Pelican Parts]

The gray wires get plugged into the black/blue wires for instrument illumination. They also carry the power for the engine compartment light and the rear license plate lights. It should get +12V when the parking lights or headlights are on.

Brown is always ground. Always, always, always--unless someone has been monkeying with the wiring.

Green/white is, I think, oil temp. Nope, that's green/black. The only green/white I see is in the engine bay, or running to the driver's side (I think) seat belt sensor. Oh, and there's another one going from the wiper switch to the wiper motor.

Red/white is always switched power, gets +12V when the key is on. It powers the instruments, among other things.

Blue/white I only see once (in the 74 wiring diagram). It goes from the flasher relay to the turn signal light in the tach.

How sure are you of these colors? Remember that they can fade or darken with age, heat, and exposure to petrochemicals. (This is mostly a problem in the engine bay though.) Are these wires that go to the connectors on top of the center tunnel?

Good pictures could help. Though we've just gone through this exercise this past week; check recent threads about wire colors for some pics and more discussion. That car was also a 75.

--DD