There are probably several of the Dultmeier wagons around Manning from that era but I can't think of who has one right now.

I'll ask around.

This may be a longshot but the Dultmeier company in Omaha, NE is part of the same family business (I think) that use to be in Manning.
http://www.dultmeier.com

You could try e-mailing them to see if they have an old wagon on display.

When your father gets the wagon restored I'd appreciate it if you would take a couple of pictures of it for me to add to the Manning History web pages.