The back can is obviously for a two stage regulator and it is blue. I think that the V66 Navy was chrome, not blue.
I don't know if there was any other Voit that was blue other than the 50 Fathom, but as I mentioned, I don't know much about Voit.
As far as I know, 50 Fathoms were single stage. You just can't installed the two stage mechanism on a single stage can without doing some machining.
Swapping front and back covers was very common back in the day, but the kind of machining (or painting blue) it would require to produce that regulator was not the kind of stuff most individual divers would do back then.
One of several possibilities is that it could be a factory assembled Frankenstein regulator. Many regulator were assembled that were never showed in catalogs. A lot of people look down at Frankenstein regulator, but in many ways I think they can be a lot more interesting than what came out in catalogs.
And Frankenstein regulator are very vintage. I assembled my fair share of them from a large box of parts and regulator components that we had in the storage room in the back at Divers Service Center. This was in the early 70's.
You can PM Greg he may be able to give more information.
---------- Post added January 25th, 2014 at 06:46 PM ----------
I should add:
I have heard many stories from Sea Hunt aficionados and collectors that some of the stunt divers would swap DA Aqua Master back can and bodies with the Voit single stage front covers. The US Divers Aqua Master breathed a lot better than the single stage Voits. Voit was sponsoring the Sea Hunt show, therefore the stunt divers had to use Voit regulators or at least they had to look like Voit.
In that situation I can see a stunt diver back then going through the trouble of having the back can painted to look similar to the front.
So, maybe what you have is a real collectors item. It might have come straight out of the Sea Hunt filming studios... Maybe this was Mike Nelson personal regulator...
Note: In case it is not obvious, I am kidding in this last post, but stranger things have happened. :shocked2: