Primed spoilers, P/N 2068151 and 1239743 may be received with no obvious mounting provisions for the CHMSL (Centre High Mounted Stop Light).
Examination of the mounting area will reveal two small raised bumps. With a small sharp blade (exacto knife or equivalent) carefully trim away surface skin to reveal the moulded-in threaded inserts.
Do no attempt to drill new holes, install inserts or use sheet metal screws; material displaced by such modification will usually result in distortion of the top surface.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.