Car Stereos: CD Cartridge Serial Number, mercury mountaineer, ebay search

Question
QUESTION: We bought a 1997 Mercury Mountaineer. Since it was used, we did not receive the CD cartridge with it for the 5 disc changer. I've tried so many different sites I'm ready to cry. How do I go about finding out what the serial number is so I can purchase the correct one?

ANSWER: Is this a factory Ford/Merc Changer?
Have you tried going to the dealerships?

---------- FOLLOW-UP ----------

QUESTION: Yes, it is factory. My husband called the dealership, but they stated the replacement would be somewhere around $60. I see similar ones on Ebay all the time for a fraction of the price, though, and didn't want to spend unneccessary money.

Answer
Understood. AS there are quite a variety of model/serial numbers on these players, it's impossible for me to figure out which one you have. As the dealership is likely intimately familiar with which unit you have, try asking them for the part number...or a written quote to replace it.. once in hand..take the part number to your ebay search engone and have at 'er.  
Sorry I'm not much more of a help that that. :)