Most AFBs had a number stamped onto the passenger side front foot but a few (Pontiacs, some Mopars, etc.) did not. Almost all had a casting number cast onto the driver side of the body on the outer side of the float bowl, and a casting number cast onto the top surface of the airhorn on the passenger side, plus numbers stamped on the top surfaces of the boosters and accelerator pump nozzle. I have quite a number of AFBs plus the original Carter spec sheets what carb are you wanting number for and which numbers specifically?