Maybe this will help. My car is a 71 z.

Lower left green wire is for turn signal which is R/W in the harness

Lower right wire is reverse which is R/B in the harness

Upper green is tail light all blacks are ground. Which is G/W in the harness.

The other light is brake. However I installed another 1157 socket So I would have both of the top lights tail lights and brake lights. I also installed led bulbs.

Hi Patcon , here are some Fairlady Z series’s wiring , hope it helps you a bit .
 

Kats

Thanks Kats