Dave03GT:
Your car has mufflers that are located about under the back seat. The '05 has mufflers that are after the axle/gas tank. If you're a good welder, you can make things fit but it is going to be a big job. If you pick up any Mustang magazine (Modular Mustangs & Fast Fords or 5.0 or.....), you will see the difference between the two exhaust systems. I humbly suggest that you consider other/easier options (but you can thank your buddy for the kind gesture of offering his mufflers to you).
Chris