Firewall Holes

-MC is master cylinder

-The oval one is for clutch rod if its 4 speed, if auto it has a body plug.

-A is body plug unless you have manual windshield washer pump. In that case this would have a molded rubber plug with two hoses in it. Its an oddball size plug and wont come in a body plug kit. You can find them but they are kinda pricey for what it is. Just an uncommon size.

-The one marked speedo looks like a hole for one of the firewall insulation retaining pegs.

-B I believe is speedo cable

-C I think is emergency brake cable.

Most wiring passes through the bulkhead. On some cars there were additional wires running through the firewall. One example would be a car with resistance grid type rear defrost. These usually had an extra heavy black and red wire to handle the extra load.