Catalina steel tanks?

[gomi_otaku]

I've been in contact with someone about buying a couple of steel 80s they have- he claims they are Catalinas. As far as I know, Catalina only makes aluminum tanks. Did they ever make steel tanks previously? They don't show up on any comparison lists of tanks that I have looked at- just Catalina C80 and S80 in the aluminum list (which doesn't clarify anything, what is the difference between a C and an S?...)
Any info?
gomi_

 

[shark.byte.usa]

C80 is neutrally buoyant when empty with a 3300 working pressure. S80 is a standard 80cf aluminum tank. I have one of each, noone ever fills the C80 to 3300, so I get screwed