Rally Dash Wiring Harness Questions

I was wrong about one thing... mine is a 1971 factory chassis service manual. Covers Challenger, Dart, Charger, etc.. Sorry I have no means of scanning these pages. Ports 'M' and 'W' inside and outside the bulkhead get confusing where manual trans requires tying a reverse indicator lamp into this circuit. You might find 2 wires together on the inside and only 1 or none on the outside of 'W'. As best I can tell, the wire to you brake warning switch on proportion valve is in port 'M' outside. B1A and B2A are in 'W' and 'Z', relative to B1 and B2 of manual trans reverse lamp switch mounted on that transmission.
Your inst' voltage regulator does get it 12 volts at switch on from a weld splice of 3 blacks and a pink. Every one is a different awg. Q2 black from ignition switch is 12awg. Black to fuse box is 14, pink to wiper switch is 16, black to inst' panel is 18.