For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition
65 WarningPiston, Connecting Rod, and Bearing Removal Engine Block Cylinder Block Piston Assembly
Special ToolsEN-43966-1Connecting Rod GuidesFor equivalent regional tools, refer toSpecial Tools.Rotate the crankshaft to a position where the connecting rodbolts are the most accessible.Mark the connecting rod and cap with the cylinder position.Also mark their orientation. This will ensure the caps ...