Hello GVS and Dutch,
Thank you for the replies.I now have a pretty good idea where the cap was located. I need this information for a modelling project on which I am working. I started working on aircraft in the RAAF back in the early 1960's. Aircraft on which I have worked include the Australian Sabre, Canberra, Dakota (C-47 ) Lockheed SP2H Neptune and Orion and F-111. I still work on the restoration of aircraft at a small museum at a base called Amberley near Ipswich, Queensland, Australia.Aircraft that I have helped restore are a Douglas A-20G-20, Douglas DB7B (looks like an A-20C ), Catalina, Canberra and at present am working on Winjeel which is an Australian designed radial engined basic trainer.
Kindest regards,
Don.