The real reason the K-37 #497 was traded for the K-36 #482 I believe less to do with the engines ability to handel the curves as the boilers age and ability to handle the rolling grade profile on the D&S.
Having fired the 497 only twice on the D&S I can say that it was frightening how close the cab awning and armrest comes to the rock walls say 4"! But the 1903 boiler of the #497 was breaking between 9 & 13 staybolts per month at the end of its career on the D&S. That's alot of downtime to pull off jacketing and to bore and rivet new staybolts.
The problem is that the boilers on the D&S get alot of cycling the water is sloshed forwards and back much more then the steady climb out of Chama where the engine works much better as I hear.
Colorado Narrowgauger in Bavarian Exile
Thor