I swore I was going to stay away from this list because of the unprofessional, boorish, childish, and profane behavior of a couple including one of the moderators, but there is so much inaccurate information being bandied about that I felt compeled to respond.
The D&RGW did double head K class engines across both Lobator and Cascade in the 30s, 40s, and 50s. I am looking at two photos of the San Juan crossing both bridges with a K28 and K36 with deep snow on the ground. So it did happen, if not on a regular basis at least a few times when operations required.
Also, don't forget that everytime a rotary was operated, one of the K's pushed Rotary OM or OY with loaded tenders and auxiliary water cars. I will have to check my data, but I would guess that a rotary with two tenders comes close to the weight of K36 or 37.
I cannot make any comment on the condition of Lobato, but I felt the history needed to be accurate.
Jerry Day
Longmont, CO