Vintage Double Hose

I've seen 3 main types of bodies for the Aquamaster series of regulators. The first was the the type with no hookah port at all, just a little stub of material where the 2nd stage was. The second was an unmachined hookah port, and the third is the normal threaded hookah that is most common. When did the second variety come about?

The reason I ask is that I have a body of the second variety that has the Navy Approved style of 2nd stage, and an unmachined hookah port. This makes me think that it's too early for a DA Aquamaster, but too late for a Navy Approved. I would like to get an idea for where this exists in the timeline.

Thanks!

Probably about 1958. It is possible USD assembled DA Navy's from the newly revised body to draw down DA Navy parts.The Navy did not accept the DAM into service immediately because of some performance issues they had with it so they could have been built exclusively for the Navy. The one I have is allegedly an ex navy regulator. Thats my best guess.