It's a nice find for your son, too bad it's a repo. In the early 70's Dodge came out with the "Gold Duster" automobile.
As a avertising gimic Everyone sold came with a bag of "Gold" coins, I found a Brasher Dabloon(spelling) in my front yard,
Thought that I was rich!!!!! Nope just a sand cast fantasy coin.....I'm afraid thats what you have there.............HH