track width and K-locos

We say that the width of a narrow gauge is 3 feet. But, of course that is not correct. If it were, the locomotives could not go around a curve because of the fixed driver's line. Here on the D&S the MOW fixes the width to be 36 3/4 inches. Last summer, in the Durango yards, there was track past McDonald's which had spread to 37 1/2 inches. A derailment forced the MOW to respike that piece.
I do not know what the CTSRR uses for width. But, I know that their curves are less than D&S.
For five years Bradshaw ran the 497. It's extra length may seem to be minor, but still it was a "rail-straightener" So, another reason for it to go off to Chama in exchange for the 482.