If its not a Formula S the two holes in the fenders maybe for the "Commando V8" emblem...If my mmemory serves me correct the two holes for the Formual S emblem are vertical not horizontal like yours. Have to check my car to be sure. Anyway below excerpt is from Car Life Magazie, June 1965.
The Formula S was a special option package available
starting in 1965 and was available through 1969, (although it lost it handling/sporting roots from 1967 on, just like the later Shelby Mustangs.) It consisted of the following optional equipment:
* Commando 273 4bbl V8 engine, 235 rated BHP
* Heavy duty rear springs (6 leaf, 115 lb spring rate)
*Heavy duty front torsion bars (0.87 inch dia)
* Front anti-sway bar
*"Firm Ride" shocks
* Heavy gauge 14 X 5.5 in wheels
* Special Goodyear "Blue Streak" tires, 6.95 X 14
* Simulated "Mag" style wheel covers
* Tachometer, 6000RPM
* Speedometer, 150 mph
* Special Formula S badges
* Low restriction single exhaust with
no muffler (just a rear mounted resonator!)
* Cars with automatics got higher
shift points
Suprisingly, the Formula S package did not include the
well known "racing stripes", or the "wood grain" steering
wheel. Both were additional options.