Hello fellow Y-block enthusiast. My name is Mike Kelly. I am 74 and live in Southern Oregon. I have owned Y-block powered cars since the early 60's. I own a 56 Bird that I bought in 1970. It is driver quality with parts from all three years of the little Birds. Almost always driveable, and never finished. This forum has a great amount of knowledge, keep it going. Question, I have two Ford factory iron 9425 B intake manifolds. One has the firing order and cylinder numbers casting on the intake runners, along with the 9425 B casting part numbers. The other manifold has only the part number casting 9425 B. Otherwise, they are identical. What and where were they used?