I have been through the pit about trying to add a changer to my factory unit. I have finally found a solution. Ford factory stereo is a kick off of audiovox and they do all the aftermarket stereo upgrades. Anyways, if you go to the audiovox website, they have cd interfaces fairly reasonably priced for those of you that don't want to do the fm modulator way. They just plug into the back of the factory radio if they have cd controls on it. Email me if you have any questions on anything.
Doc