One more eBay photo for you, this time from a black and white negative. It shows CP 4241 in front of the roundhouse in McAdam on June 25, 1978. I am not sure when the roundhouse came down in McAdam but it must not have been long after this photo, given the apparent lack of a roof.
4241 is ahead of another C-424 unit, followed by two other units that might be RS-18s. RS-18 CP 8731 is the unit on the right track.