A steering knuckle gearbox assembly comprises a body having a housing portion having a cavity defined in the housing portion; a mating portion connected to the housing portion and being pivotably mountable an axle frame of a vehicle; and a mounting portion for having a steering link of the vehicle pivotably mounted to the mounting portion. An input shaft is rotationally supported by the housing portion and extends into the cavity at its one end and is operatively connectable to a drive axle of the vehicle at its other end. An output shaft is rotationally supported by the housing portion and extends into the cavity at its one end and is operatively connected to the input shaft at its other end. The output shaft is offset in height from the input shaft. A steerable track system for a vehicle is also described.