I have recently completed an O scale model of a "Redler" 50 ton coaling plant for the O scale Dulth Winnipeg & Pacific. These were rather unusual structures, apparently more common in Canada than the US. The DWP had two, one in West Duluth and one in West Virginia, MN.
Here is a link to a page on our web site that has some details about the coal tower model and a Weaver 2-8-0 conversion, also for the DWP: http://www.scaleartmodels.com/dwp13.html
Here is the loco and coaling tower together on the workbench.
Thanks for looking,
Scott Anderson