My 2001 300M has a very bad top end engine noise/rattle. Engine starts, runs, idles. I bought the car in this condition because I have a 97 intrepid parts car with a 3.5. I have subsequently been told that the cast iron block engine will bolt up but will not run with the 2001 electronics. Is this correct or is there anyone who has made this work. I would like to complete this project without spending another $1000 on an HO engine.