Looks like we lost boss429kiwi back at the end of 2011! I hadn't noticed this thread until resurrected today. I agree, great "barn" and nice stable of horses!
I'd have to say that the Mustang is not truly a muscle car, but a pony car. 'Bird and Mercury qualify, probably. Muscle Cars being intermediate sized cars of mid-'60's to early '70's with largest engines Detroit allowed installed. Camaro, Firebird, 'Cuda, Mustang -- all pony cars. 'Vette, Cobra sports car. Thunderbird is personal car. Impala, Galaxie full sized. ALL are nice cars!! IMHO