Greg, I took some video in 2005 when I spent a good part of the summer @ MRSR. One enlightening scene shows 10 leading 91 out of Morton with a passenger consist on a Saturday morning. All looks fine as the train nears until you notice that the guy standing in the doorway of the Climax is bouncing up and down maybe 3-4 inches. When the Heisler passes, it appears smooth as silk.
The one geared engine that I have a soft spot for is also numbered 10 and also calls the Mineral area home. She is former Pickering Lbr. Corp. 3T Heisler 10 & has been on display in Elbe for many years. Spent the summer of '72 with her on the 8.6% of the K&HV in Northern California & came to really like the engine.
Although she was pretty tired then, she ran cool and gave us few real problems.