Bill,
The one being pointed to is the tank's vent. You need that one (unless you want to decrease the size and shape of the tank ). The other one is the sending unit for the fuel gauge. The one by your thumb (that is you, isn't it? ) should be the fuel pick-up for an early tank. A banjo fitting would have been attached there, but the dip tube inside the tank could have come loose. Does your tank have a drain plug on the bottom? If so, you can use that port for more fuel.
John
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