picked up a Lionel Winner 1011 Pullman this week on the cheap. It was packaged with a late Hafner-Wyandotte box-type tender and this tunnel, which I believe is Dorfan or Fandor?
The ends and sides are both lithoed and textured and it appears they may have been slotted for a cross bar to hold the tunnel open. Definitely small O gauge or OO gauge in size.
Anyway, it was basically free with the purchase, nice to make out on a package deal once in a while. If anyone knows the manufacturer, let me know.