Wonders never cease! Here is the brass connector for connecting the fuel tubes to the tank. I guess that's what connectors do, they connect things through a connection just connecting this, that and the other thing. These unscrew in the center and have rubber inside to keep the fuel where it belongs, inside the connection.  This item is also listed in the Mk3 parts manual under J for fuel, item #33, 53, and 98 totaling 5 each per car according to the manual. The part number in the Mk2 book is different. So until I can get my hands on the back end of a Mk2 and check out its tubes to tank, these might just be for the Mk3s only.