I just installed a 300zx master cylinder. I was installing it, and the middle port that has the capped hex is a different brake fitting than the other 2. Also, can you confirm which port goes to what brakes…as its not marked on the ports…and I am worried its different from the stock s13 setup, since the capped port required an adapter to get it to work. (why would nissan have 2 different brake fittings on the same master?)
from my understanding…the one with two ports reaaaly close to each other are for the fronts(left and right) and the further port closest to the front of the car is for the rear brakes (which split up somewhere in the hardlines to go left/right)
if your car has ABS -> then you only use one port for the front and one port for the back which they both go to some ABS actuator and all the lines split up from there.