Kelsey-Hayes proportioning valve for A body

early Factory disc/drum system requires both - the big one with many connections (post #1) is actually a distribution valve and does not protortion the pressure. The small one that takes two fittings in post #4 is the proportioning valve and is located about a foot toward the rear of the car from the distribution valve in the line to the back brakes.
I don't know about the A-bodies, but on the B/E-bodies the proportioning valve and distribution block were integrated into one unit starting with model-year 1972.