WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Measuring Final Drive Pinion End Play
Courtesy of GENERAL MOTORS CORP.
Inspect the end play with a feeler gage for proper clearance. Proper clearance is 0.24-0.62 mm (0.009-0.024 in).
If the clearance is out of specification, replace the differential assembly (116).