I am sure i have heard of some very late built Challenger in 1970 got the Elastomeric bars, but not enough that it can be confirmed, and they are rare on a 71 as you mentioned
But i really like them on your car Scott
they look awesome
have you toyed with the idea of Blacking out the top section of the bars like the Elastomerics came with from factory ? this would make the bar blend in with your grille treatment you have got going on
And can you post a rear shot as i would like to see how it looks with the rear Elastomeric bar against the back of the car please.