I saw the A12 there. Kind of sad how its displayed IMOThe only thing I think was never cross tried was between KC-135's and KC-10 on keeping the Blackbird fleet fueled on missions, as I have never seen a Blackbird in photos or video's behind a KC-10 only the KC-135's.
I have seen the lone YF-12A, the SR-71A both at the USAF museum then the SR-71B at Kalamazoo Air Zoo. I would love to see the SR-71C or the bastard bird as it was known by the crews, what made it special was that it was the only hybrid SR ever made, what made it a hybrid, simple Lockheed took the rear remains of the crashed 2nd YF-12A and grafted a SR-71B nose to it. The real story behind the derogitory name was that it had a nasty tendency to yaw out of control if you wasn't on top of your game. The C is on permanent display at Hill AFB in Utah which is a little out of the way from Ohio to go see.
Then you have the model that started it all the A-12 I would of loved to seen the lone trainer that Lockheed built of the 12 but that is never going to happen as it is on display in California.