I have a set of y-block rocker arms that came off of a 312 engine that I bought. The previous owner said he could never get the engine to run right. Since the engine has G heads and a B manifold, I believe it is out of  the 1957 Ford Fairlane. The rockers are not ECG high ratio. The only markings on them are the number 70 on the forward side and a random letter on the other. The letter is not the same from rocker to rocker, but the number 70 is. What I want to know is, what is the origin of these rockers and what is the lift ratio of them? I plan to rebuild these rockers and sell them if I can, and I need to know exactly what I would be offering, since I don't want to unintentionally mislead any potential buyer. Can anyone help me with information on these rockers? They appear to be in really good condition with hardly any wear, so they are a good project for rebuild. Thanks for any help!