Originally Posted by FiNkEy
i was wandering how hard it would be to swap my 3.0 with a 4.0 and what modification i would need to do if any to make it work? thanx
Engine, transmission, PCM, engine wiring harness and exhaust Y-pipe are all different. Those are the major parts. Be sure to shop for a compatible year donor - a 2003 4.0L would be the best donor for your 2003 3.0L. 2001~2002 would also work without much trouble.
2003 3.0L came with either a 7.5" or 8.8" rear axle, depending on the model. The stronger 8.8 is the factory unit for 4.0's and would be a better choice for your swap, too.