GMC Sierra 1978 Manual Gasoline mileage: 83 KM GMC 1978 manual transmission, engine (6 Liter LY6) fully refurbished. A top-tier vehicle. - Safadi headers - Denali fans - Manual transmission - External axle differential - Fully flashed and refurbished - Has nano ceramic coating - All gauges are working - Tires are almost new - Suzo AC - Sound and heat insulation - Abu Tair mufflers - A complete check-up has been done on the vehicle from bumper to bumper.