The earlier AD's with Huck brakes used different sized lines, and therefore T junction blocks than the later Bendix brake system.
I ran into that when I ran a drill through the frame of my '49 and punched all the way through it into the T fitting. I thought, no sweat, I have an extra one from my '52. No dice. Different size fittings. BTW, Bendix showed up on 1/2 tons in 1951.
Carl
