The dual-action fuel pump (47-55) was a factory option (and could also have been added/changed later).
Both styles of fuel pumps came with a glass bowl filter on the top of the body. A GM (AC)
accessory gasoline filter was available for attachment to the inlet of the carburetor (the fuel line was bent to clear the earlier horn and/or to keep from having to cut/fit the end of the fuel line).
Those glass bowls served two purposes - to filter particles and to allow you to see if you have water in the fuel (at least that is what I found them to be good for).
