I wouldn't even concider the vinyl top as rare, i'd say i see more vinyl top cars than not. Out of the 21 or so 440 M-code notches i have in the registry ONLY 4 are NON-VINYL tops!!!!
It's hard to guess how many 4 speeds VS auto were built. In some cases of '69 notches it goes either way. I would guess maybe 1/3 to 1/2 of the 325 were automatic cars. (extremely rare for 4 spd and A/C, don't even think i've ever seen one).
So lets guess 125 autos built. I'd say your guess is close at 20?
