OER Parts offers a wide selection of Valve Cover Components for your 1978 GMC C15 Suburban. OER Parts offers 1978 GMC C15 Suburban Breathers, 1978 GMC C15 Suburban Hardware, 1978 GMC C15 Suburban Hold Downs, 1978 GMC C15 Suburban Kits, 1978 GMC C15 Suburban Spacers, and 1978 GMC C15 Suburban Valve Covers.