300M, Concorde, LHS and Intrepid - From 1998 to 2004 - All parts are interchangeable on these cars with the obvious exceptions:
- Body panels, head and tail lights, obvious things like that are not compatible.
- 1998-2001 and 2002-2004 wiring connections were varied and are not compatible, so you'll need to match the two production runs (for example: if you have a 2003, you need wiring from a 2002, 2003, or 2004).
All years and models mentioned above are compatible and are interchangeable. As mentioned, functions such as memory and heat will require you to remove the body harness from the donor car and add it to your own, or you can splice in the functions with your own wiring.
The wiring should be present in your car already for an automatic passenger seat. At least it is on my 2003 SE. If it is not, you can easily add it, by simply splicing into the two power wires for you driver seat connector and running two wires from there to your passenger seat.
Very simple project, so don't over think it or worry! You really can't hurt anything, worst case, blow a fuse fuse, which are a dime a dozen.