I got a 03 Excursion with 230K miles and have been thinking of upgrading the current engine but have found a low mileage 05 6.0L and wanted to know how interchangeable the 05 engine with the 03 engine?

 

It will drop right in , if it doesn't come with the harness all you have to do is sort out the wires and connector for the ICP sensor, just undo some tape and pull the wires loose from the wire loom and then put it in it's own loom to go to the pass side valve cover because that is where the ICP sensor is on the 05 engine. Make sure you have the 05 intake because the 03 intake won't fit on the 05 because of the High Pressure pump gets in the way/I believe/. Just make sure in the future when you get parts for the motor you get the 05 parts, certain things are not interchangeable/ water pump-glow plugs- are probably the only ones you will run into in the future.