I just had this question about 10 days ago and Gilly answered for me. Search for the subject to read more. The connector is a 10 pin rectangular connector being fed by a wire the diameter of a typical outdoor extension cord. I found that wire tucked in near the wheel well on the passanger side, behind the trim, just as Gilly said it would.
BTW I got a great deal on a MB branded changer with bracket, cover and cassette on eBay. $163.50 including shipping. The bracket was for a different model but a little bending fixed that and it works great! Thanks, Gilly and all who replied to my question on this subject.