OER Parts offers a wide selection of Oil System & Parts for your 1977 GMC C25 Suburban. OER Parts offers 1977 GMC C25 Suburban Bypass Valves, 1977 GMC C25 Suburban Dipsticks and Tubes, 1977 GMC C25 Suburban Filter Adapters, 1977 GMC C25 Suburban Oil Coolers, 1977 GMC C25 Suburban Oil Filters, 1977 GMC C25 Suburban Oil Pan Baffles, 1977 GMC C25 Suburban Oil Pans, 1977 GMC C25 Suburban Oil Pickup Tubes, 1977 GMC C25 Suburban Oil Pumps, and 1977 GMC C25 Suburban Oil Senders.