Many of us who love the Denver, South Park & Pacific have enjoyed the photos of the 23 DSP&P Mason Bogies. Sadly, all have been lost to the scrapper. I was surprised to find on a recent school field trip with our kids that there is actually one remaining Mason Bogie left in the world...and it's in operation!
I notice the Torch Lake must have been an early one as it has Stephenson Valve gear. I think all the DSP&P bogies were Walshaert ( not right spelling) valve gear. I think there are some miniature models( live steam) in the US. Paul R.
Small correction: the video states that Mason Bogie No. 57 was displayed at the University of Iowa. It was actually displayed instead at Iowa State University. Thanks to Justin Kerns for pointing this out.