This model dates back to the early days of N scale (late 60s / early 70s) and has had various importers over the years (AHM first, Con-Cor, Wathers and Model Power later on). It presumably vanished from the face of the earth at the same time that Roco did (circa 2000). The Con-Cor version (pictured above) came with a slightly different work car.
The two pegs (pictured below) are inserted into the windows in order to "operate" the boom and hook.
The prototype for this model is likely an Orton 160-ton crane such as the one pictured below. Orton first started building railroad wrecking cranes in the mid-1940s, which sounds about right for this particular model -
