Steve Connor, Bob Shock, Ben Greathouse, John Degani all hired on as fireman in the 1920's and were not promoted until 1946 or so. They spent over 20 years on the deck. I too heard that some old guys - especially those on the Durango end never let thier firemen run. Some of it was the nature of the roller coaster profile between Durango and Chama (it was real work going both ways), some of it was "I spent years to get on the right side and I'm not moving!" I've heard stories that some guys got promoted with very little right side time under thier belts.
Things seemed to be different over in Alamosa. Eldon Morgan has said several of his engineers let him run when he was still firing. There were a lot of younger engineers over in Alamosa.