Heavy Duty Steel Tube Aluminum Air Fin Dual Circuit Auxiliary Oil Cooler replacement for Peterbilt Trucks With Paccar Engine. Always reference your oem numbers prior to buying. Review all photos and dimensions as there may be more than one option for your year, make and model. Installation should be completed by a trained professional. Applications: Kenworth Truck Models: T800, W900 Our Part Number: 21543 Core (Finned area) Dimensions: 33-3/8” x 4” x 1-3/4” Replaces oem Part Numbers: N4147001 Notes: Robust steel tubes with aluminum fin construction Staggered tube pattern and high performance air fin design to maximize cooling.