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 WarningControl Valve Body Assembly Disassemble (Gen 2) Automatic Transmission Unit Control Valve Body
Control Valve Body Assembly DisassembleCalloutComponent Name1Control Solenoid Valve Support2Control Valve Body Bolt-M5-x-40.5-(Qty:-1)3Valve Channel PlateNote:Inspect the channel plate bolt pass through holes for damage or brinelling. Any damagewill cause incorrect pressure switch operation. Replace ...