Sorry, I'm afraid I don't know how you could prove the car's build date without paperwork from the factory, dealer or previous owner. Hopefully the Aurora website guys can help with that.
Here are a couple long-shot ideas.
1. Have you tried contacting Ford Motor Co. for information about the car, based on its VIN? I can't remember exactly (
I was just a teen when the Auroras were built), but I thought the Aurora was sold through Ford dealers (
like the original Cobras) as they also used Ford-supplied engines.
2. Have you tried contacting
Global Automakers? Its predecessor, the Association of International Automobile Manufacturers (AIAM), used to publish an annual VIN handbook. Maybe they can provide some independent validation of your VIN number and consequently the car's age.
3. Have you tried reaching out to the Shelby American Automobile Club (SAAC)? In addition to original Cobras and Shelby Mustangs, the club and its members are quite familiar with the many replicas that have been produced. Try posting your question over at the
SAAC forum.