What’s the exact process to identify a real 66 Formula S Barracuda?

My friend had the car in 1972 or '73. As I recall the interior was stripped out except for the buckets, might have had the back seat. I don't remember any emblems although it may have had the 383-S hood trim. It would be interesting to go back and check the VIN and trim tags! I took it out on the highway and spun the tires through first, second and part of third!