Hi,
We discussed that RGS and/or SN being in Denver was possible a while back but there was no belief (IIRC) that it happened. Sorry I can not find the correct search words to find the original thread.
On page 158 of Colorado Rail Annual #14 concerning the Creede Branch, there is reference to correspondence between Creede and Denver refering to shipment of silver that had occurred in SN and RGS box cars and why D&RG equipment was not used.
Apparently they were loaded at Creede for Durange and Silverton. Before shipment began, the New York & Chance Mining (shipper) changed their minds about which smelter to ship to.
So RGS and SN equipment does appear to have made Denver but very, very seldom.
Doug vV
For What its worth.