A grass mowing machine has a frame with an adjustable width toolbar including a center section and left and right outer sections telescoping into the center section. A pair of cutting units are mounted to lift arms pivotably connected to outboard ends of the outer sections of the adjustable width toolbar. A hydraulic lift cylinder is mounted between an inboard end of each lift arm and the adjustable width toolbar at a selected mounting point in the center section. The mounting point of the center section is aligned with a mounting point in one of the outer sections to provide a specified toolbar width suitable for the cutting units.