The markings on the CR/NS 6764 would be what I'd be interested in - specifically the classic intertwined 'PRR' logo (minus keystone) that showed up on both Conrail and Norfolk Southern locomotives. I can't seem to find whether any of the SD40-2s acquired from CR by NS had either of the possibilities rather than the normal text 'PRR'/'NS' markings.
I'm actually shocked that over the years that none of the manufacturers (none that I've recalled seeing, anyways) have bothered to implement such a transition paint scheme to the SPFs that don't mind modern power... There have been very few with just the regular font (only one Atlas SD35 and a Lionel SD80MAC to my memory)...
