Wagner it is, This is a circa 1950 Wagner Truck Crane. I admittedly don't know much about it, but thanks very much to John Frances, Don MacKenzie, and George Murphey for putting some information together for us.
Circa 1950, Mixermobile Manufacturers offered this distinctive 10-ton capacity crane. Powered by Chrysler gas engines in the crane and carrier, its 50-foot pin-connected boom could be folded down by one man to keep the machine under permit size limits while eliminating the hazard posed during travel by a protruding boom. It also had two patented features: a conical mount for the upper works and easily deployable, hand-cranked outriggers. It was evidently not a success.
Davwingman had this first. Thanks to Brian Kelly for the photo.