Yes, I posted the update in post 18.
The A/C was the first clue.
My knowledge base is 30 years old, but I don’t think you could order A/C in a 66. I think a dealer might have installed a few.
Not saying somewhere along the way somebody added it for creature comfort, but the original early model Shelbys were pretty close to street racers with little extra.
But the 66’s already were less true-racers than the 65s.