Knock At Low Speeds
WARNING: This page does not describe the selected car, but rather 58 other vehicles, including the 2003 Saturn Vue, 2003 Saturn L300, 2003 Saturn Ion 3, 2003 Saturn Ion 2, and 2003 Saturn Ion 1. However, it is still accessible from the selected car via links, so may be relevant.
A low speed knock can be caused by a differential case side gear bore that has worn oversize. Inspect the side gears and the differential case assembly and replace the components as necessary.