I'm sorry... but that looks like Sn. 61-7844... i know my RS-71's, but she is a beautiful bird, where can i find that repaint?
It's number was originally 980, but after it was handed over to NASA in 1990, it was given a new designation (NASA 844), though some sources still refer to it as #980. I'm no expert though, I'm just going by what I read.
As for the repaint, at the moment the only place you can find it is on my hard drive.
