I will respond with the disclaimer that I don't have all the information that some others may have on this subject, so feel free to correct, those in the know.
They tell me that the D&S railcar is still on the property in Durango. It was used for transport for "Ah, Wilderness" guests, a line-side resort. That service was suspended a few years ago.
The White Pass railcar was built by the same company who built the Durango car. It is still in use running from Fraser, BC to Lake Bennett, maybe even in daily use.
Tolland.