Well I found the listings you speak of. Dorman part #s W18197 and W18196. They give some rather generic application info:
GMC 3000 1961-1964
GMC 3500 1961-1964
GMC TRUCK 1953-1960
I wonder if they would fit my '55.2 Chevy 6400? Rock Auto doesn't seem to list my model of truck at all, which is a bit strange.
With rock auto I went with the picture and the wheel
cylinder diameter. Perfect match for my 1946 2 ton.
Jeffrey
