I think I have it......on the vin will read BP29....which means :
Make = B - Barracuda
Series Number = P - Barracuda (1966)
3rd & 4th digit Body Style = 29 - "Sports" Coupe (as opposed to simply "coupe")
That's from the Early Cuda website and trying to make sense of it. Even then it doesn't explain that this defines a Formula S, but I think it must, because you either have a Coupe, or a SPORTS Coupe.