Holly Molly! Don't laugh ( at least no more than I am) but I'm 90% certain that I'm the original owner of this OP's Aqualung Aluminum tank. Here's the story if you have time on your hands:
Once upon a winter of 1974~75 this young crazy kid decided to sign-up for a YMCA Skin & Scuba Diving course in Ottawa Ontario Canada. During the 8 week-ish course and in anticipation of the spring open-water final exam, I purchased (in addition to the Aqua-Lung Wrap-Around Mask & Rocket Fins which I had) an Aluminum Aqua-Lung 80cf tank, Aqualung Conshelf Arctic Explorer Regulator, weight belt and a Parkway 1/4" Shark-Skin Wet Suit, boots and 3-finger gloves. That was it. Nobody but sissies dove with a PFD in those days. Moreover, they were super expensive and heavy given that they had their own tank to inflate it. Another buddy purchased his gear not too long thereafter. More on that later. Everything was purchased from an outfit called: Laurentian Trading Post in Ottawa.
Anyways, a few years did go by diving in freezing fresh water lakes looking at pikes, bass and weeds. The novelty was all fun but now we're in the mid 1980's. My 1/4" Shark-Skin Wet Suit shrunk and consequently I was looking at diving south going forward. Because of career, Yada-Yada, I moved to west-island Montreal.
In the early 90's I upgraded my skill sets to ACUC Level 4, thus the ACUC VIP sticker. My then ACUC instructor became my new diving buddy. Many trips, Bay of Pigs, yada, yada. After many years of un-use, I donated my Aqualung Aluminium tank to the Scuba school. It was called: Les Anémones Bleues.
My original diving buddy of the 70"s decided to pack-up his diving fun for whatever reason. He gave me his yellow Aluminum Aqua-Lung 80cf tank and his Aqua-Lung Calypso regulator which I still have (un-used) to this day.
I have no clue as to how my grey Aluminum Aqua-Lung 80cf tank got to where it is, but the resemblance and chronological date stamps are more than a coincidence. That's my story and I'm sticking to it.
Dennis