In the 1988 and 1989 model years, 'J' vehicles commonized from 25mm and 22mm diameter strut rods to 22mm diameter strut rods on all 'J' cars as follows:
ORIGINAL EQUIPMENT STRUT ROD DIAMETER *1988 1989
Chevrolet 'J' Level 1 & 2 22mm 22mm Chevrolet 'J' Level 3 25mm 22mm
*1987 and prior model year vehicles are not listed. Most will be equipped with struts with 25mm diameter strut rods, but some may be equipped with struts with 22mm diameter strut rods.
All service stock in GMSPO (for J vehicles) has been commonized to the 22mm diameter strut rod, with specific internal valving for individual applications. Therefore, when ordering replacement struts from GMSPO, any struts received will have 22mm diameter strut rods, even if the vehicle involved was originally equipped with struts with 25mm diameter rods.
The difference in strut rod diameter has no noticeable effect on vehicle handling, performance, or strut durability. Therefore, when replacing an individual strut on a vehicle (due to accident damage, etc), it is not necessary to replace both struts due to different strut rod diameters.
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.