The brass piece stays on there. The aluminum nut I ground down to make it shorter. I drilled the end of the cap put the pressure gauage on and used silicone to seal it up. The air nipple, was a screw style (O'Reillys) that came in a two pack. The rubber freeze plugs have not been a problem, no leaks. I have held 6lbs in my motor for over 15 minutes, after I sealed up the leaks.