66 Dart Owners thread
"Rare" is a relative terrm. Considering the 1200 or so built, any mid year introduction of a part would make it rare in my opinion. The majority of those cars were certainly built early to satisfy demand with numbers tapering off as they tooled up for the new model and year.
Regarding the car you mention, it is definately rare in my opinion. However a car that was built in LA with AC (which I assume this one was...), Is not as rare as a car built in MI with AC. IMO, the rarity of that car is the power disc brakes.