I picked up a new fuel pump from NAPA over lunch break this afternoon. Staring at this thing sitting on my desk it just doesn't look right-- there are three ports or tubes on the bottom instead of two. One is a threaded female compression type port which I presume is the outlet to the carbs. The other two are male hose type tube shaped thingies, one of which, I presume must be for fuel in from the tank. What would the third one be for?