Probably not too many of the original 68 RR's & 68 Super Bee's they were the entry level, affordable muscle cars for under $3000, that was the original concept anyway, that kind of defeats the purpose of buying a RR or Super Bee & adding "air conditioning" back then, it was almost as much as a 426ci Hemi option... Just my thoughts, I have no idea of production #'s, I'm on my 13th 68-71 RR's mostly 68's & 69's, I have only had 2 with A/C & a big block, both 70 & 71, I've had a bunch with autos, power brakes & power steering, I would think the A/C would be some what rare in a 68... But I don't know that for a fact...