Where do the blue and brown wires that operate the RS headlight relays and that also connect to the diode harness under the dash, penetrate through the firewall? They separate from the front wiring harness about a foot from the firewall, but I can find an empty hole. I guess I could put them through one of the firewall pad plastic pin holes rather than drill another hole.
Also, where would the oil pressure tube to a console gauge setup penetrate the firewall? I'm thinking about changing over to console gauges shortly.

on my 67, the brown and blue wire penetrate right next to where the wiring harness attatches. For the oil pressure tube, you'll have to drill a hole and install a grommet.

bonecrusher,
All 67 and 68 RS cars have a stamped hole about 1 inch in diameter below the brake master cylinder. Non-RS cars did not have this hole. Both years had a rubber grommet that installs into the firewall and protects the wiring (or in 68 vacum hoses) from chafing. 67 has two very small holes in the grommet and 68 has two larger holes for the vacum lines used in 68.