Ted,
Actually, the Billmeyer & Smalls car of which you speak has been detrucked and is in storage along with the two other cars at the Nevada State Railroad Museum yard in Boulder city, Nevada. Prior to the State getting them, they were, as you said, at the Gold Spike near Hoover Dam. However, that was also prior to them being on display at the Clark County Heritage Museum in Henderson, Nev. They were originally brought to the Southern Nevada area back in the 1940s when a colorful character nick named "Doby Doc" brought them down from Northern Nevada, along with the locomotive, in a rather notorious escapade that I have posted previously. The equipment sat for many years on display at the Last Frontier Village,(near the site of the present day Fontier Hotel in Las Vegas) until moved out to Gold Strike.
The Billmeyer& Smalls car is in very rough shape and has been so for decades. However, it will arise again one of these years in the forms of a replica that I am constructing to pull behind Eureka, as Eureka used to pull that car on the E&P.
Dan Markoff
Las Vegas, Nevada