OER Parts offers a wide selection of Valve Covers for your 1988 GMC R3500. OER Parts offers 1988 GMC R3500 Aluminum Valve Covers, 1988 GMC R3500 Chrome Valve Cover, 1988 GMC R3500 Transparent Valve Covers, 1988 GMC R3500 Logo Valve Cover, 1988 GMC R3500 Finned Valve Covers, 1988 GMC R3500 OE Valve Covers, 1988 GMC R3500 Billet Aluminum Valve Covers, 1988 GMC R3500 Low Profile Valve Covers, and 1988 GMC R3500 Tall Profile Valve Covers.