Classic/Antique Car Repair: 55 buick gas pump, windshield wipers, 55 buick

Question
on the bottom half of the gas pump it has and inlet and outlet what are these for and do they need to be hook up cause i only have one line coming from the tank for the gasoline

Answer
This is a two stage fuel/vacuum pump. This pump was designed to provide vacuum to the windshield wipers during periods of heavy throttle and load to keep the wipers working like when climbing a hill. One side of the pump was connected to the intake manifold and the other side to the vacuum line to the wipers. The diaphragm used to rupture and the vacuum would suck the oil out of the oil pan so a lot of times these were disconnected.