From what I have been told no single two bbl was available in 57 so if a 2 bbl was wanted a J-2 intake with the outboard carb holes blocked off,if it still has the outboard carbs and there is a plate between them and the intake someone did it for gas mileage or other reasons, If its missing the two other carbs I have a J-2 intake with correct carbs with aftermarket linkage I will sell. Jeff