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Genuine GM parts have one of these marks:

California Proposition 65 WarningExhaust Manifold Heat Shield Installation
Install the exhaust manifold heat shield (2).
Caution: Refer to Fastener Caution.
Install the 3 exhaust manifold heat shield bolts (1) and the washers and
tighten to 8 Y (71 lb in).
...
Fuel Tank Filler Door Replacement
Fuel Tank Filler Door Replacement
Callout
Component Name
1
Fuel Tank Filler Door
Procedure
Position the fuel tank filler door to the full open position. Using light
outward sliding pressure on the filler door, ...
Throttle Body Installation
Install the throttle body (2) and a NEW throttle body
seal ring (1).
Caution: Refer to Fastener Caution.
Install the 4 throttle body bolts (3) and tighten to
8 Y (71 lb in).
...