During chassis lubrication, accessibility of the idler arm grease fitting is limited.
The grease fitting is accessible from the rear of the splash shield by using a grease gun with a long flexible hose.
For your information, Page OA-5 of the 1984 "S/T" Truck Service Manual identifies the steering linkage lubrication points.
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.