So how rare, if at all, is the A66 option on a 70 Challenger? I just went through my fender tag last night for the first time. It has the A66 code on it, along with the V9X Black Bumblebee Stripe (no longer there). I was told by the seller that the engine was changed (he indicated it had been a 318 but the fender code indicates 340-4). It used to be an automatic with console but was changed to a 4 speed with no console at some point in its past. The black vinyl roof indicated by the tag is no more. Since there have been a number of changes compared to the original set up in what appears to be the higher production color for 1970, I didn't (and still don't) think the car has any unique history compared to others that are shown on this website... but I thought it would be worth checking.
By the way, my thanks to whoever put the tag decoder program on the website (in 2002??). Between it and one that was referenced in another thread on C-C.com, I think I was able to ID the meaning of all of the fender tag codes. Pretty cool.