'66 Darts are heavy. '66 Barracudas are heavy. Niether one is lighter than a factory stripped down Duster. With the sole exception of the early Valiant, it is a myth that early A-body cars are lightweights.
Dodges typically have a 2-3" longer wheel base than the comparable Plymouth. An early 64-66 Barracuda has that heavy rear window, fold-down seat, etc. Newer models added safety equipment that was not on the first generation. All that adds up.
Dusters and Demons had flipper rear windows instead of roll-ups. The Feather Duster and Dart Lite also had aluminum bracing for the hood and decklid. A dart Lite hood followed me home from a swap meet once and it was considerably lighter than an all steel hood. I once thought of using it on my 69 Barracuda.
My vote is a strippo 63-66 Valiant. Under 3000 lbs.
