That's the 5/8th PS nipple. The 'vert I'm parting and my Dart wagon are both PS cars and have said nipple. The problem is I might have to use the Dart PS box in my 67 Charger (which is a PS car) as I think all I have for pumps are the ones with the large nipple on it. Let me inventory what I have as I don't want to cut myself short when I get ready to start the Charger.