I think there is a difference between the hose fittings of that era, but perhaps not the hoses themselves. If you look at the original Calypso above (Akimbo's picture above), you'll see that the fitting going into the first stage is far from the standard, in that it directly ties into the end cap of the Calypso. It wasn't until the second generation that the standard fitting was used for the Calypso.
The same can be said for the Dacor Dart. The original Dacor Dart had a non-standard fitting going into the second stage. I know, as I got really frustrated with this regulator--trying to get it to breathe easily--and cut it off; that was a mistake as the fitting is unique to that regulator. It wasn't until the Dart II that the fitting was more standardized.
The original Healthways ScubAir and Scuba Star regulators were tilt valves, and had a much different hose fitting going into the second stage. These fittings are not interchangeable with the later downstream fittings used in the regulators of the same name. I have several of these regulators too.
I would peg the standardization of the LP hose/fittings as somewhere around 1965. That is when you could start interchanging the LP hoses on different brands of regulators. It was just before the time that the cave divers started using octopus regulators too (I didn't use an octopus until I dove with Larry Murphy/Sonny Cockrell in the Warm Mineral Springs Underwater Archaeological Project in February of 1975). Many divers used different second stages for their octopus regulators, and same even used the tilt valve Healthways Scuba Star as their octopus, even though it had a different second stage fitting, it had a first stage fitting that was universal at that time. I used a MR-12 first stage with a Sportsways second stage during the early 1970s, and never had a problem with interchanging hoses.
Once the longer octopus hose was introduced, standardized fittings were absolutely necessary. This was a problem for some of the overseas manufactures, such as Nemrod (Snark II) and Poseidon Cyclone Super 300 regulator, were equipped with metric fittings. Therefore it was difficult to use foreign (to the USA) manufacturer's regulators as we had to use their specific second stages as octopus regulators. With just about all the USA manufacturers, we could interchange second stages.
I've included several photographs, two of divers using Healthways single hose regulators (Limons Osis with a Healthways ScubAir, me with the speargun and a Healthways Scuba Star, and the fitting on the original Calypso regulator. The other photos of the Dacor Dart don't show the hose fitting (I'll have to take that if you want to see it), but show the fitting is very different than the standard today. The diagrams of the AMF Voit Viking 40, Conqueror and Explorer II show three different fittings in the 1960-62 era (from Fred Roberts, Basic Scuba, Figure 3-37). So there was still experimentation going on then.
SeaRat
