550 cat. Sigal tube. In the last two years, there has been alot of rebuilts done to this trk. New head, injectors, wiring harness, water pump, oil cooler,fuel pump & fuel lines, new heater hoses, new radiator, new air cooler, new steering box,new air compressor, new Carrier bearing, new steps/boxes, new air bags on sleeper, new Holland F35 fifth wheel plate, new rear ends (325 gears) new air bags, new air cans,new brake & drumes, new rear bearings & race, s-cams, slack adjusters, APU Rig master (perkins motor) excellent condition. Interior mental condition. Alot of rockwood dress up, new blue tooth stereo& speakers. This truck has been well cared for and ready for work, A must see, Any questions fill free to call 307-251-2023 steve