streamliner question!

My wife has a friend at work whose husband found a streamliner display at a local convention. He realized that he owns that exact train and wonders how old it is, how much it’s worth, etc. The caption underneath the train reads-“This train, made by General Trains, Inc. of Chicago, is one of the only two- rail, standard gauge trains ever made. Standard gauge trains by other manufacturers used a three rail track.” The train appears to be a passenger type used by Union Pacific. Thanks for any info- I’m still new to the hobby so my railrod history isn’t the best.
-Frantzy

While waiting for experienced answers, try going into the search box,upper left corner,and plug in standard gauge.

I recently bought this very model…3 cars, marked Union Pacific No.123 US Mail on the engine car and all 3 cars marked General Trains Inc…track width is 2 1/4 " on inside of rails…the cars measure roughly 21 to 23 " each…No one at the antique shop nor subsequent railroad fans (visiting at this shop)offered any information. My interest is more in streamline and industrial design in the 30’s in general rather than model trains as such. I can’t give you any more detailed info and hope that some expert and kindly disposed enthusiast can help us both.