Beginning January, 1987, a new style side roof rail weatherstrip is used on 1987 'G' models without Hatch Roof Option. These new weatherstrips exhibit very little appearance change, however, they are thicker and softer to minimize wind noise.
The new weatherstrips are available through the Parts Department under part numbers:
20737658 - Right Side 20737659 - Left Side
These part numbers supersede current part numbers and apply to 1978 thru 1987 model years.
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.