CDOT has asked train manufacturers to show whether they have locomotives and train cars that can handle the steep grades, high altitude and sometimes low temperatures of the Denver-to-Craig route
I get they probably want the new DMU's etc. But I wonder if a GP40 with a HEP car and some heritage equipment would be a great way to test the waters since you know it will already work in this environment vs trying to re-invent the wheel. They may have missed a golden opportunity to buy something dirt cheap with the SLURG liquidation a while back... IIRC there was a couple of Budd built cars that had been 'tunneled' for MARC commuter service. Again, this isn't to be permanent. I know I see a lot of railfans on other sites who don't think we should invest in anything new and just keep what we have ( harupmph! Chargers are Evil! harumph, just use 50+ year old clapped out F40s)... But a stepping stone is needed to see if the service (which has been gone for over 50 years) is even viable.
I know they use the Stadler FLIRT's in service in Dallas on some steep flyovers, but those are short and I think they have a running start. I know the Moffat isn't a steep railroad compared to what I'm used to running, it's just the length of the run would probably beat those little gensets in those to death.