The hub and drum are all one piece cast together. I have never seen drums sold without the studs in them, but that doesn't mean it isn't possible. Keep in mind that the 64 and 65 used one style front drum, and the 66-67 used another. You can put the newer style on the 65 and it works fine, but it looks completely different. There was only one size front brakes on the 64-67 A-body Buicks, so there shouldn't be any choices. Only variation is the larger wheel cylinders for the GS compared to the regular Skylark. All of the 64-67 Buick Abodies came with finned front drums, regardless of what you may read in some of the old litterature floating around out there. The Chevys didn't have finned drums.