K-27 in Black Canyon of the Gunnison

Gawd, do I love saying "Black Canyon of the Gunnison"! Don't sound much more "Out West" than that!
Gil Lathrop recounts in "Rio Grande Glory Days" that the D&RG ran a test train with a class K-27 through the canyon in the 1920s. The engineering department officials put gauges on the several steel truss bridges in the canyon, and, alas, the engine exceeded the limits of what the bridges could handle. It was determined that engines in the class could be transferred "dead-in-consist", i.e. main rod off and in the train as freight.
I saw this test done in early 1982 on the Animas High Bridge in 1982, with 481. The engine was run at 10, 15, and 20 mph. Yeamans was running . A wild little ride to say the least. The gauges did dictate a lower speed limit on the bridge fortunately.