I am in no way connected to this offering on Ebay®.
https://www.ebay.com/itm/1963-Ford-Fairlane-AUTOLITE-4100-4-BARREL-CARBURETOR-1-12-C3OF-AB-HIPO-289/312625681311?hash=item48c9f1539f:g:-fcAAOSwXexc5Yz8 (https://www.ebay.com/itm/1963-Ford-Fairlane-AUTOLITE-4100-4-BARREL-CARBURETOR-1-12-C3OF-AB-HIPO-289/312625681311?hash=item48c9f1539f:g:-fcAAOSwXexc5Yz8)
This assembly has been commercially rebuilt before so it is missing its assembly tag and the top cover assembly is not correct BUT the main casting is stamped C3OF-AB. That was the original HP289 carburetor model for all of preproduction engines during late 1962 through mid May 1963 production or about the first 1000± HP289 engines. (Regular production of HP289s started March 1, 1963.) They are super rare now in any condition. This is only the second core I have ever come across.
This model was replaced by the C3OF-AJ one in mid May 1963. There are many calibrated parts differences between the suffix AB and AJ models.
If you have a car (1963 Fairlane or Cobra are the most likely candidates) with a 1963½ engine assembled before about mid-May 1963 this would the original model for your engine. Check your engine assembly date and or the engine serial number.
I have the C3OE intake manifold and C3OE spacer to complement it. LOL