Thanks for the info. I found that the tank I was looking at was a 60, and was also told my my grandfather that he has a 72 in the garage that i’m going to try to find and dig out now. My next Question is as far as usabliity; I’d like to have them as back up tanks. Is there a place I can update the valves to a more modern style din/yoke valve and would you recomend checking out another dive shop to see if they will do hydros on old tanks like this?