I just got a '56 3100 truck with a bad engine. I found an engine from a '54 that I have running now. I note that the '54 engine has slots, like a vent in the valve cover where-as the covers on the '56 don't....I'd really like to use the '56 cover as it's in better shape, but I don't want to cause a problem, like blow-by or something.....any advice ?