A harvesting header is operable in a first mode of operation by engagement of a skid at the cutter bar for cutting along the ground. A gauging system operable in a second mode includes four ground engaging members supporting the header such that the cutter bar skid plate is at a controlled distance from the ground. The ground engaging members include a long skid and removable gauge wheels are carried on an elongate beam pivoted adjacent the cutter bar and extending to the rear of the frame and adjustable by an upstanding telescopic mast up to a position to allow the cutter bar to run on the ground. A resilient suspension can be provided at the rear of the beam at the junction to the post. The location under the table allows a very high adjustment of the cutter bar in the second mode.