Ok then....
My 2 cents worth:
A Bodies never had from the factory:
Cruise Control, Power Windows, Passenger Side Remote Mirror, Factory Tape Player, 6 Pack option.
I make this statement based on my 30 plus years messin with mopars. If I am wrong...cool. I live to learn and help others!
However, Factory Cruise Control is an easy add on... have it on all my auto Darts.
Power windows would be nice.... but a major conversion. (I am gonna try it soon though).
As for the rarest A Body option: I would guess the Factory Sunroof then AM/FM radio.
Later,
Bruce B.