1963 AC Bristol
Before there was a Shelby Cobra - there was the AC Bristol. It was an aluminum bodied sports car that came with an anemic 120 HP six cylinder engine. In 1963 - when AC lost their Bristol engine supplier - Carroll Shelby squeezed a Ford V8 in it and the Cobra was born. Bristol would ship the chassis and body to California where the Metamorphosis took place. It went on to win many races and they later released them with Ford 427 V8's. They were absolute Corvette eaters.
An 1963 AC Bristol with 49,000 original-miles original ownered car went for $260,000.
Shelby only made 1100 Cobras. Original have gone for over $1,000,000 at auction.
In 1963 - when I was in 10th grade - I wrote to Carroll Shelby. He mailed an original specification sheet to me. That was 50 years ago. I can't think of anything else that I have saved 50 years.