The picture I believe is for both drums and discs, but the discs got the metering valve and proportioning valve added to the system.
I have the after Jan 1, 1970 combination valve and the metering valve and my car stops great. I did use just the drum brake distribution valve at first and the car still stopped ok, but tended to have a little nose dive on braking. Upgrading to the '70 and after distribution combination valve and with the metering valve made the car stop without the nose diving. The metering valve or hold off, allows the rear drums to engage before the front discs. If you have 4 wheels discs, I believe the drum unit is your ticket. Front discs and rear drums generally need the metering valve, but as I said, I went without it. I just prefer the stopping without a little nose dive, but that's just me. Both distribution valving units brought the car to a stop exactly the same, albeit the slight nose dive.
I did find, at least for me, that I needed to change my front brakes lines to the disc brake part numbers for the line fittings to screw into the after Jan 1 distribution block without leaks.
