A Shunt truck, also known as a Spotting tractor, Yard truck, Yard Dog, Yard jockey, mule, etc. is an articulated vehicle consisting of a towing engine (tractor in the United States, prime mover in Australia or truck in Ireland, the United Kingdom, Canada and New Zealand), and a semi-trailer hitch to carry the freight. A semi-trailer does not trail completely behind the towing vehicle, but is attached at a point that is forward of the rear-most axle of the towing unit, so that some fraction of the weight of the trailer is carried by the rear axle(s) of the prime mover. This arrangement requires both tractor and semi-trailer to be distinct in design from a rigid truck and trailer.
The Shunt truck of this design seems to be a distinctly North American. There are only 2 manufacturer that use generally the same specs, both are located in North America.
Distinctions between a Shunt truck and a regular Truck are several and noticeable: