Looking at the car closely, I noted that in pencil on the underside of the car it is written “was N&N 94” and “Roundhouse RB 2935.” The N&N would be the Newton & Northern of Newton Guerin, and the Roundhouse notation relates to the model of the MDC Roundhouse trucks modified to fit the car. The sides are hand scribed, nicely but if you look close things are a little uneven. It has Scale-Craft doors and some Graceline parts on the frame. It might be based on a Graceline car, but it is hard to say.
It came out nicely! This photos were taken before the decals had been completely settled in (as I was taking other photos), it looks even better on completion. Note in the bottom view I saved the areas that William Johann had written the notations given above. May it give good service to owners beyond me.