I had all "AMF Voit" when I started out in early 70's. Had a Nemrod speargun and then Mares guns and equipment. Details are hazy for me now, but didn't AMF Voit morph into Mares at some point in the 70's?
The Abyss and other Mares models along the way are essentially a Voit MR12.
Most manufactueres well into the 80s did supply tanks, valves, spearguns, full kit. Including Scubapro (Healthways), Voit, Nemrod, U.S. Divers, White Stag and on and on. And they largely made their own stuff, it was not rebranded from another source and sold by multiple companies with just a decal change and maybe some exterior styling changes. Today even the major brand outsource.
This has been a larger change than most realize affecting all aspects of life. When companies manufactured their own products in their own factories with their own employees then there were multiple supply lines. Well, now compare that to today when most companies outsource, be it vacuum cleaners or scuba gear, often to the same out sourced entity and multiple supply lines become one. Then you are standing in line for toilet paper or waiting months for a part!
James