Here is the rear brakeline with the check valve and the regulator that adjusts the pressure differently for the rear brakes while using front disk brakes. There is only the one original Brookville (notched) crossmember at this point. The "notch" is evident in the upper right corner where the master cylinder sits back into the front of the crosmember. That notch was boxed in with the cutout piece reversed but I wondered if the crossmember was weakened. You can also just barely see the drill-through holes with cotter pins on the rear four bar mount nut. All the nuts on the four bar mounts were treated to a cotter pin.