Ford 4100 carburetors were produced from 1957 to 1968. The first design in 1957 was quite different from the later models and uses a different accelerator pump among other variations. 1957 models only use kit CK7425. All carbs from 1958-1968 use the same pump and other kit parts.
Ford carburetors are generally identified by the number on a metal tag. The carbs are variously marked as Ford, Autolite or Motorcraft depending on the year of manufacture. Model 4100 carburetors were also stamped with part of the carb number on the edge of the base, near the front on the throttle body.
Ford tags and stamps are discussed here.
Ford 4100 carburetors are marked with the venturi area in inches cast into the driver's side of the float bowl. These range from about 1.08 to about 1.23 square inches.