Following up with GrandpasJimmy, I looked up the parts info for 55&57 GMC 1/2 ton with "driving front axle" and found the drawing below in the 55.2-60 GMC Master Parts Book. I know this is GMC info and you are asking about Chevies, but MAYBE they are the same????
The slave cylinder does look like it is different sizes on front and rear in the drawing. I can get GM part numbers for any of these parts and maybe one of the part number gurus can find the parts.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
