Unfortunately, the catalogs GM Parts Direct and many of the dealers who sell online are made by a third party and are not all inclusive. Those RPO codes are for the springs, not the shocks. There is a reason all of those web sites want your VIN so they can double check with the real GM parts catalog before shipping your parts. You need to have a dealer look it up by the VIN to make sure you're getting the right parts (you could even try calling Flow Auto Center that run GM Parts Direct). There are different shock and spring part numbers for SWB, LWB, wheel size, etc. The aftermarket makes it seem so simple because they make one part and say it fits all but that isn't the case at the factory. That's why those RPO code descriptions say: computer selected suspension component.
