I also was surprised to see a black widow Geep still around in 1973. When I was a San Joaquin Division brakeman in 1968/69 GP-9s were very common, along with quite a few F's, but I don't recall seeing any in black widow paint even then. Of course that was a long time ago and my recall probably isn't what it once was.

As much as I liked the Geeps they did have one drawback for the head brakeman: in the winter, which could be very foggy and cold in the valley, when underway the front door on the left side was not very good at keeping out the cold, wet air. The cab heaters sometimes were just so-so.

Thanks for posting all the S.P engine photos, Steve.