Crew Calling

HI all:
Well this is my first venture into the discussion since coming back from the Salt Lake City Narrow Gauge Convention. Much of your discussion about the calling of crews leads me to ask some basic questions about the whole crew calling practices and how they changed over the years. From reading one of Norwoods books I gather that there was a dramatic change in the calling practices sometime during his tenure at Chama. He doesn't say when but I assume it was in the 1930's. That was when the crews began being assigned to Durango and Alamosa and mearly turning around at Chama. It was also when car repair was discontinued and Chama was degraded. My question is exactly when was this and what were the circumstances. I know that the arrival of the K-36 and K-37s would have altered the situation since the K-36 was too long at 68 ft to fit in the 65 ft stalls and I suspect that the K-37s were too heavy for the turntable at 307000 pounds as I have seen K-36s riding it but never a K-37. I suspect, though have never seen a figure, that the bridge of the turntable may have been rated at 150 tons, the K-36 is just under that and the 37s over. The depression and traffic could have also been a factor.
What are your thoughts?
Frank