Hi Mick
Well a nice pair.
The Rio Grande did not use Alco FA1 in real life only the EMD F and Alco PA series in the Aspen gold, silver and black liveried 'Zephyr' trains... they also did not use the longer E8s ........ but that would more relevant to rivet counters.
The Grande used the F and PA locos as passenger power as part of the Zephyrs (Primarily 'The Prospector', then The Californian Zephyr, later The Rio Grande Zephyr as well as the PA unit used on the short lived Yampa valley Mail.). The F units were used for the 'Ski Train' that ran from Denver to the Winter Park ski resort.
As they became older and revenue from the 'Zephyrs' was declining and the passenger fleet was shortened and eventually finished, the railroad would put the gold and black striped jobbies into freight consists...... they became a wee bit dirty and a bit sorry for themselves, but to the Rio Grande's credit, they did clean the F and PA units more than the other diesels!
This the front of one of my F3 'A' units as it draws in at Beaver Creek Station
View attachment 211907