I got an Oceanic first stage and I am having trouble identifying the model. it has four low pressure ports and two high pressure ports and the only thing stamped on the regulator body is the serial number. I have attached photos I took of it and would appreciate if anyone could shed some light on the model, year, type (piston, diaphram), and specs (Balanced or unbalanced?). If anyone can supply me with the schematics or service manuals I would be very thankful.