GM-44416 is used to determine the shim thickness needed for the differential drive pinion to achieve the correct pinion depth for proper operation. Correct pinion depth is crucial for proper axle performance and service life. GM-44416 consists of the following: GM-44416-1 Differential Side Bearing Discs (2 required) GM-44416-2 Front Pilot Washer GM-44416-3 Gauge Block The gauging components are used with previously essential GM-21777-1 Arbor and GM-21777-43 Stud Assembly to determine a normal pinion height. The final shim thickness is determined using available Service Information.