Ken: I agree that we are looking at photos of two different cars (Bruce's post of SL&M #23 and Jeff's photos). My records show C&S #23 Baggage Coach as being 34' long with 24 seats, weighing 17 tons, built by Bowers, Dure & Co. for DSP&P in 1880. Rebuilt with one end platform removed in 1915. Sold to Herr Rubican Supply Co. 2/1923; to Salt Lake & Mercur #23 as standard gauge. This dealer was renamed A.T. Herr Supply Co. in 6/1926.
The C&S sold Combines #22, 23, 25, 27 and coaches #57, 81, 120-131, 132-136 and 138 to Herr in 1923. Then in 1924 the C&S sold combine #25 and in 1926 combine #26.
I found a builder's photo attributed to Herr Rubican in the American Car & Foundry Collection, St. Charles, MO. It is lettered Salt Lake & Mercur #23 as well as Wells Fargo & Co. Express. Photo was taken on a transfer table and is identical to the photo that Bruce posted showing the car in Utah. I also bought three stereo views of this car derailed (upside down view shows underbody detail) on the SL&M at a Salt Lake City book store.
All this material is included in the B&L article. I too feel that we have more to learn of this mystery, expecially in view of the fact that the photos were made in the 1920s, after the SL&M was reportedly abandoned in 1913.