Dick:
That was Flanger OK which is on the C&TS and was used on the first C&TS flanger train in 73. Flangers tended to be assigned to specific crews and runs and OK was the Crested Butte flanger for years. OJ which is also on the C&TS was used on the Baldwin branch and the run to Sapinero. The video was shot by Irv August and is available as a tape but I do not think it has been done as a DVD yet.
In 1891, a Gunnison newspaper reporter rode a D&RG flanger train from Gunnison to Crested Butte with engine 251. He describes how he could not see the caboose from the engine cab when the flanger was kicking up snow. When I first saw that video of OK in 52 it reminded me of that account. Temperature hit 56 degees below zero that year at nearby Taylor Lake and that was the last year a rotary was used on the Crested Butte branch.