OER Parts offers a wide selection of Car Care Products for your 1990 GMC R3500. OER Parts offers 1990 GMC R3500 Cleaning Supplies, 1990 GMC R3500 Buckets, 1990 GMC R3500 Grit Guard Basic Wash System 3.5 Gallon Black Pail With Yellow Lid, 1990 GMC R3500 Grit Guard Basic Wash System 5 Gallon Yellow Pail With Black Lid, 1990 GMC R3500 Universal Pad Cleaner, and 1990 GMC R3500 Grit Guard Dual Bucket Washing System.