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

stillrunners said
My 1966 Form S did not come with either trunk cut outs.....but hey who knows why....and pretty sure my 1965 Form S I bought in 1975 did not as well or I would have those parts in stock still.

Of the 7 '66 Formula S's and 2 others I've had with the 14 X 5.5 wheels, they all had the cut out in the divider panel.