The USD diver's reg pictured above is definitely an Aquarius. As indicated above it is no longer supported and perhaps more importantly they tend to be a bit challenged with the number of LP ports.
The Mk 5 pictured on the previous page looks like one of the last Mk 5's produced in the mid 1980's. It has the heavy 3300 psi yoke, the SPEC swivel cap, and should have a 5 port turret and 2 HP ports.
The second stage is the 080 "High Performance". They are unbalanced and use the same basic poppet design as the R190 and R390 but are very well made and breathe very well. It also appears to be of mid 80's vintage given the design of the rubber purge cover.
Scubapro still provides support for annual service parts and other "soft" parts. DIN conversion kits are also available and other parts such as the yoke and knob are standard SP parts used on other first stages. The parts you can't get new would be the main regulator body, swivel cap, LP port turret, retainer screw and the piston. Of those, none should wear out due to use unless badly abused. But in that case, there are all kinds of used MK 5's floating around as well as several clones (the Mk 5 was one of the most widely copied first stages in history) that could donate the needed parts and they go for very little money on e-bay.
In short, the Mk 5 is a lot like the Boeing B-52 - it will probably outlast the regs that replaced it in service.
I agree that if a dealer says they cannot get parts for a Mk 5 they are either not a Scubapro (or TUSA) dealer or more likely, are claiming parts unavailability to get you to buy a new regulator. The SP rep for a shop I used to work with used to give the owner hell for buying lots of Mk 5 and Mk 10 annual service kits when he coudl have been selling those customers new regs. Scuabpro regs are the ultimate in durable goods and when properly maintained they will last for a divers entire career.
