I was looking at one of those old photos, and the paint looked quite faded. Then, I remembered the climate at Edwards, where the plane spent most of its operational career. I have to think that the UV index at that place was pretty horrific, do to the super-low humidity. I wonder if the paint faded so rapidly, this would explain why nearly every picture seems a different color. Of course another problem is that color films in that era were not the most color accurate, plus printing press printing is never accurate.