The outlet used on your '69 is identical to the one utilized on my '64, but the face plates are different. The oulet is a readily available Leviton pictured below:
I ordered my receptacle from Westside Wholesale Electric
on the web.
You are a little more fortunate that I have been in that there is at least a similar cover plate being manufactured by Bell. Mine has the screw-on cap and I haven't been able to locate one anywhere on the net. The current offering from BELL
is aluminum that has been powder coated gray -- I couldn't find mention of a raw aluminum. The powder coated model is pictured below:
These are the components that I ran across as I was searching for the needed parts for my Overlander.
Good luck with your search!