Rarest A-Body Option?

I would say the Hemi LO cars do not count.You had to have a drag racing license to buy one.And in alot of cases you had to know someone to get one.The average Joe could not walk into the Dodge Dealer and buy one.So would the LO cars be a option.
I would have to say the M code 440 Darts and Cudas.Anyone could have ordered one.
OH YA DONT FORGET THE 70 DART R/T's.....LOL