Do you have a Zenith carburetor on the GMC 228 - does it have the clamp with a bevel in the middle?

Do you have a later 235 Rochester with a center bolt (wing-nut attachment from top), or do you have an earlier 235 Rochester with an air-cleaner-clamp around the top of carburetor, but no center bolt on the top of the carburetor?

Also, what are the diameters of the tops of the carburetor (and/or the diameters of the holes in the bases of the air cleaners)?