I am doing a frame off resto on a 1976 f100 swb 2wd and noticed that it has two lines running from the tank to the front of the truck, one is for fuel to fuel pump other is a vent line from tank to whatever its called, my trucks original tank came with an eec valve on top of the tank which from what I gather info on is like a roll over valve or emmisions valve I don't know, my question is.. I ordered the new tank without the eec valve, do I need that vent line or can I do away with that all together?