The '65 Mustangs used a 4100 Ford Carb 480CFM with automatic choke and 1.08 venturis,the Mustang Hi-Po's used a 4100 with 1.12 venturis (600 CFM) and a manual choke chances of finding a new one would be slim,closest Holley would be an R1848 used on earlier Fords but not on the Mustangs which is available new.