During ring and pinion or bearing service, selecting the correct pinion shim is critical to the operation and service life of the axle. GM-51629 allows technicians to measure the initial pinion bearing shim required on Dana 190 mm, 200 mm, and 220 mm axles. These axles place the pinion shim under the inner pinion bearing cup, instead of between the inner bearing and the pinion. To determine the required shim, the gauge plate for the axle being serviced is installed in the inner bearing cup bore, along with the inner bearing cup and cone. The arbor and side bearing discs are then installed in place of the differential case. The GM-8001 dial indicator is mounted and zeroed on the arbor when the plunger contacts the gauge plate. The plunger is then moved off the gauge plate, and the dial indicator reads the required shim.