This barn held two very different 1968 Mustangs — a base six-cylinder car, and a genuine mid-year 428 Cobra Jet Fastback GT that Ford built specifically to homologate for drag racing. Both need real mechanical work after years in storage, but only one of them is one of the rarest production Mustangs ever built. See what a side-by-side barn find reveals about how differently the same model year could turn out.