Thank you for the information and the research you obviously spent some time in completing. I first became aware of the existence of Wabash UP cars when visiting my son in Los Angeles a few years ago. We went to the Allied Model Train store (it was still open) where many of the Hollywood stars purchase trains for their hobby. Frank Sinatra was one customer that comes to mind.
While in the store I noticed an O gauge metal (presumably aluminum, but possibly brass) consist of UP cars, one of which had the "Wabash" in UP red over the entrance door of the car. I didn't check the name on the side of the car and was going to talk with the clerk concerning manufacturer details. However, we got caught up in other searches and left without gaining additional information.