GMC - S SERIES - 1978 RSS 1978 GMC S SERIES ELECTRICAL SYSTEM:ALTERNATOR/GENERATOR/REGULATOR 1978 GMC S SERIES SUSPENSION:MULTIPLE AXLE 1978 GMC S SERIES VEHICLE SPEED CONTROL 1978 GMC S SERIES EQUIPMENT:OTHER:LABELS 1978 GMC S SERIES SERVICE BRAKES, AIR:DRUM 1978 GMC S SERIES WHEELS:MULTI PIECE