Cliff:
Wish I could have been there to see OB. I have been researching and writing about it since 1971.
((All I have heard is OB will only be use for demonstrations.))
One bit of information that might get lost in the shuffle is that the D&RGW had another piece of pile driving equipment available in the 20s and 30s and when the line was being rebuilt for the K36s and 37s. The D&RGW purchased a pile driver attachment for their steam ditchers. It was first used on OX and then transferred to OW. Both were used in driving piles on Cumbres Pass, Marshall Pass, and Poncha Pass and all over the narrow gauge. OB was used, but it did not have to do all of the work.
For example, in 1927, when an avalanche took out a trestle on the Anthracite branch north of Crested Butte, the D&RGW used a ditcher with the pile driver attachment to rebuild the trestle.
Jerry Day
Longmont, CO