The older fellow at my local napa told me the valve in the old MC is a one way valve to keep the fluid from flowing back into the MC. This was needed because the MC is below the wheel cylinders. I have no residual valves just proportioning valve. I will add residual valves when I am able to find a MC that fits between the cross member and the steering gear box not before do not want to drill extra holes only 1/2 inch forward of orig. mounting holes for steering gear box. My brakes are working fine and with the proportioning valve adjusted just right the rear brakes lock just before the front as per inst. that came with prop. valve.