The C&S Railroad was seeking to buy Mallets for use in Colorado. Here is the info for you:
The C&S engine was going to be patterned after this Rio Grande do Sul Brazilian Mallet:
As for the D&RGW, I could only find one source of drawings for the proposed engines - it turns out they were 2-8-8-2 (funny how both lines favoured the respective smallest wheel arangements they used!!) http://www.colong.com/ So if you reletter your Mallet (manufacturer inmaterial) for the C&S…then you can pretend that the transaction did occur and they actually rambled and roared thru the Colorado Hills.