I recommend talking to a Delphi warranty shop. I've done a bit of business with Speed-o-Tach out of Concord, CA. Their website is
http://www.sotelectronics.com. They sell the factory deck, and I could swear I've heard you can install it in a pre-2003 vehicle. Not sure on the cost though - I've heard the new Pioneer systems are absolutely amazing and might be a better alternative. Good luck...
Take care,
Jerry