TC, I have a 1961 235 with a pump with that bolt. I replaced it. I think there was a rubber hose connected to it. I don't know where the hose went, always thought that hose bolt was a vac bypass or something related to wiper vac. I have seen that you have the largest library of Chevy info in the nation, you mean you don't have a pic or instructions for that pump bolt hook up? That's impossible!
