Not sure, but checked Classic Parts website. I think I see a longer snout on their cylinder. (The boss that receives the hose) As compared to Rockauto and as compared to Classics rear cylinder. If that is the case, it would possibly have better clearance.
http://www.classicparts.com/1951-59-Wheel-Cylinder-Front-Left/productinfo/71-107/#.V3rFAen6s5s

ALSO please notice on link page below how the front cylinders do not have an opposing boss, just the rears. The opposing boss is so that one casting can suffice for left and right rears. The long boss had to be centered to fit into the hole in backing plate. I am proposing that the fronts, having an extra long boss, did not allow for dual purpose casting. Which makes me believe boss is actually longer and "positioned" correctly to clear. So check out all those cylinders you've been getting.
http://www.classicparts.com/Wheel-Cylinders/products/114/

Last edited by bartamos; 07/04/2016 9:56 PM.
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