This is a small 1-barrel carburetor used on Ford 6-cylinder engines from 1961-1969.
Ford 6 cylinder engines used a variety of single throat (1-barrel) carburetors, including Holley 1904 and 1920, Carter YF and RBS models as well as the Ford 1100. Please consult the relevant sections for a visual comparison.
Ford carburetors are identified by the number on a small metal tag. The carbs are variously marked as Ford, Autolite or Motorcraft depending on the year of manufacture.