Funny I just asked this question in another post. 493 and 498 had been stored servicable inside the Alamosa Roundhouse and 497 and 481 were stored inside and outside of the Durango Roundhouse during the same time period. 497 was probably chosed because it had a full overhaul in 1967 and was used very little after that so the decision may have been based on this. I still believe that if another K-37 had been restored before the 497 the D&S would still be running them today. 497 had issues with her lead truck which caused her to have tracking issues and I believe made her harder on the track than she should have been. Once it was fixed on the C&TS there were no real issues. The tightest curves on the San Juan extention was in Monero Canyon and all the 37's ran there until the end, so negotiating the Silverton branch shouldn't have been or be an issue. My 2 cents of course.
William
aka drgwk37