Hard to get !   Part no 64.  Steam valve for D365/D375.  D405/D415.  kit built engines  . This steam valve has a threaded outlet as well as being threaded to screw into the boiler . You can also use this part along with part nos 55 cylinder & 6002 pipework to turn your production built engine into one you can take apart and rebuild without the need to do any soldering.!