If we are going to be extensively discussing preservation of potentially significant prototypes, I would nominate this:
This can be recognized as one of the EMD GP22ECO demonstrators, a significant if unsung piece of locomotive technological history, and there are already pictures on loconotes of its snazzy new livery (hopefully applied over the EMD paint to preserve it for posterity). If I understand correctly, the engine has been ‘on site’ less than a week.