Greg: I have a couple hundred RGS color slides from regular operations and RMRRC Excursions in 1947 (with RGS #20 and D&RGW #319) and 1951 (RGS #74). Also September 1951 freights with #461 and #452 and a few 1952 scrapping scenes with #42 and #461. Also have some shots obtained in trades with the late Dick Kindig and Phil Ronfor.
These are all 35mm Kodachromes which have retained their colors.A few have been published, but many have not seen print. Sorry to be so late in responding. Name your "poison".
-Mal Ferrell