Stop it Captain, now you have me considering calling that guy
I did. He's away on a trip at the moment and told me to call back monday. He sounded a little tipsy actually.
Lisa, the UDS 1 was manufactured by US Divers and had triple tanks, but with an integrated aluminum manifold/first stage/tank filling system. It had a built in J valve reserve. Complex and very proprietary in nature. The tanks have 1" valve openings so only those tanks can be used with it. It's the system I'm talking about restoring on the other site. Cool but short sighted in many ways as most proprietary systems are.
The ABS triple system was also manufactured by US Divers but used a more traditional chrome over brass solid manifold with a yoke connection on the right hand side and no built in reserve. You could throw any reg set on it but a DH would need offset hoses as the yoke is skewed to the right. The tanks were 3/4" so any modern tank could also be fitted to it.
Another one of the clamshell styles one might see is the RAID double tank system by Technisub. I believe the tanks are not standard 72's (could be corrected on that) and the manifold system is also proprietary and quite complex. Ryan at Flashback SCUBA (Sea Explorer on the other site) gave me a good look through of this system at last years Tacoma dive expo.
Some other clamshell systems are the Watergill ATPAC and Dacor Nautilus as well as the Scubapro Scuba System.
Ryan also showed me a double tank clamshell Cousteau system (the one with the DH mounted on the chest) that he recreated himself from the original. I forget the name but the rig, and the story of its build, was amazing.
The clamshells are very cool and I think they may have suffered an early demise due to the "mainstreaming" of diving to the masses. This meant more rental/vacation divers who probably didn't have the time or need to understand or care for "all in one" systems.
Of course, the "all in one" recreational rebreathers are becoming quite popular now.