When I was a kid in SLC in the late 1950's I always looked forward to the the westbound City of Los Angeles and the Challenger on the UP during the summertime. Of particular interest was the City of Los Angeles which was usually solid armour yellow except for the loco lashup, ABBA or ABA (E8's & E9's) with the trailing A unit being an orange and brown Milwaukee unit. I'll bet nobody would model the City of LA looking like that! It really stuck out like a sore thumb, but I always thought it quite exotic. As you may know, after breaking off their passenger pool with C&NW UP went with Milawaukee Road for a time. Did Milwaukee Road participate in power pools with anyone else?
That sounds about right for the Milwaukee Road. Before 1955 all Union Pacific passenger trains to Chicago traveled via the CNW (Chicago- Omaha), in 1955 they moved over to the Milwaukee Road and thats when they went to the Identical yellow scheme to help blend in the equipment. No doubt that engine just hadn't been repainted yet.
Ryan