Found some additional information on the 'Super-Cooler' that is on the '77.
It's a Texas-born and manufactured product, patented in 1968 by the Opti-Cap company. Mr Allie Holmes and his wife Chloe Holmes co-owned and operated the company in Corpus Christi, where I assume this product was also made. (The Opti-Cap had previously been patented and in production since about 1964, first known as the Kwik Chek Cap)
Mr. Holmes was a decorated veteran of the 101st Airborne. Having been severely wounded on D-Day, he was later medically discharged and returned home to Arkansas where he met and married Chloe after the war. The two moved to Corpus and started the business together.
Mr. Holmes died tragically in a car accident in 1975, Mrs. Holmes passed away in March 2017.
I do not know when production ended, but I did find the original patents and some newspaper articles from when it was first released.
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This may be the source of the screw holes on the drivers side inner wheel well on the 1968 fury...I will try to acquire another Supercooler, but I may just have to end up making one.
Searched for several hours for the Opti-Cap, but I can't find one or even a modern one that functions the same