A track system (18) of the type used to adjust the position a supported element such as vehicular seat (12) includes a pair of base rails (20) that slidably interact with a respective pair of driven rails (22). A transverse rail (24) is attached to each of the driven rails (22) so that the driven rails (22) slide together as a unit. A motor (34) is supported on the transverse rail (24) and includes a pair of drive shafts (36) emanating from either end. The drive shafts (36) carry on their distal ends' respective worm gears (38) which are contained within a transmission assembly (26). The worm gears (38) mesh with external teeth on respective drive nuts (54) which interact with a lead screw (28) that can be oriented to either remain stationary relative to the base rails (20) or can be rotatably fixed within the driven rails (22). The drive nut (54) is prevented from causing objectionable noise and premature wear in operation by the inclusion of one or two compressible washers (66).