A power steering assembly and method of retrofitting therefore includes a housing having a cavity defined therein. A drive member extends axially into the cavity and a first piston and a second piston are received in the cavity for axial reciprocation therein. The first and second pistons define at least in part first and second pairs of chambers. The first pair of chambers receive fluid under pressure to move the first and second pistons toward one end of the housing to rotate the driven shaft in a first direction. The second pair of chambers receive fluid under pressure to move the first and second pistons toward the other end of the housing to rotate the driven shaft in a second direction opposite the first direction.