Abstract: A hydro-mechanical steering differential for providing differential steering of the left and right hand tracks of a tractor is disclosed. The steering differential is powered by a mechanical input and a hydraulic input, and includes left and right outputs. The improved hydro-mechanical steering differential comprises a geared differential unit having a right output gear element, a left output gear element and a gear carrier element. The gear carrier element is coupled to the mechanical input and has a gear set meshed with right and left output gear elements. The left output gear element is coupled to the left output, and the right output gear element is coupled to the right output. A gearless hydro-mechanical differential unit has a rotatable motor powered by the hydraulic output. The hydro-mechanical has a drive unit coupled to the mechanical input and a driven unit coupled to the right output.