There should have been a round brass disk holding it all in.........just leave out the valve and "glue" in the disk and put the retaining ring back in place in front of it.
Connect your overflow (did your metal tube break off? or is it missing?) to a recovery tank; your local supplier should have one, if not, there is always J.C. Whitney............
You can use clear vinyl tubing from the hardware store, it's the same stuff they use in swamp coolers............it's nice because you can see the coolant in the hose and which way it's going; either to the tank or back to the radiator.
