These are the black composite floats used in all three of the 1966 carburetors. You should check all three of your floats. The large brass floats are no longer available. We have seen many times someone had used the small brass float that are used in the small center carburetor on the large ends and large center carburetors. Mike has been using these composite floats in his restorations when needed, they have been working out great.