Hello HO Modeler, and welcome to "The Gauge".
Surry Parkers were much, much smaller than the unit you pictured. An article and plans ran in the May/June 2003 Narrow Gauge & Short Line Gazette. McGifferts were also much smaller. One is on display at the Lake Superior Transportation Museum in Duluth, MN, by the way. I have been fortunate enough to have visited that one in person a number of years ago.
The machine in the photo is a tower skidder. These used a compound engine and usually combined loading and skidding functions in one unit, had large crews, and were a strictly high-production, big-time unit. They weigh up to 172,000 lbs. and can handle around 125,000 board-feet per day. Manufactirers included Lidgerwood, Clyde Iron Works, and, I believe, Willamette Iron & Steel Works and Washington Iron Works. The distinctive feature is the steel tower (works like a spar tree) between the boiler's stack and the front of the unit. These monsters were huge. The towers were 75-120 feet tall. The best reference I've run across is "In Search of Steam Donkeys" by Merv Johnson (c. 1988 by author and publihed by Timber Times, Hillsboro, OR). Overland produced a brass model in HO (cost around $1,000.00) and long ago, Paige Enterprise made some type of HO white metal and wood model.
They're quite a machine!
--Stu--