Abstract: A gauge for measuring the clearance between the bottom surface of the body side bearings of a rail car and the subjacent top surface of the respective truck side bearing rollers includes a central vertical frame and a horizontal cross beam carrying on each of its outer extremities a vertically movable graduated blade. Telescoping arms on opposite ends of the cross beam enable the gauge to be used on different kinds and sizes of rail cars and cabooses; and a missing side bearing adapter is provided so that gauging can proceed even though either or both of the side bearings are missing. For truck plant and body plant use special indicia are provided.