What "makes" a 66 Barracuda a Formula S ??

Hi all,

it may be a strange question, but is there anything on a 66 Barracuda that officially makes it a Formula S ?
Is there anything on the fender tag, or VIN plate ?

Or is it just a case of if it was optioned with certain things it WAS a Formula S.

I ask because I have seen a couple of 1966 cars advertised as Formula S models, but they don't carry the badge on the fender, and I'm ot certain what to look for.

Thanks,

Peter
Ok, to be a genuine Formula S in 1966, it HAS to have the fender tag with F7, and the Shipping Order number on the fender tag has to match the one stamped into the radiator core support. Everything else could be bolted on to mimic a FS.