My father has a 97 continental which has a bumping which sounds like it is comming from the rear deck or upper shock/strut mounts. The dealer claims it is something which you have to take the back seats out to access. The car does have at least one of the rear dampners leaking fluid. However my mother has a 99 sable which is now making the same sound. So I am thinking it definatly is suspension and not the rear tray which the sable doesn't have the amp, tuner etc.. that the continental does. I couldn't find anything under or behind the rear seats. I did find some large black thing on top of the shock which has a top like a nut it's probably a good 5 inches high and seems to be isolated from the shock by a rubber bushing. I know continetnals seem to be a car most mechanics know just about nothing about. Since the car shares the basic frame/unibody with a sable I am thiking it is some type of suspension flaw. But I can't find anybody who has any idea about it for sure. And since dealers aren't exactly cheap I don't want to throw money at them whicle they guess at solutions at 50-75 an hour plus parts. The dampners are several hundred to replace and are about level with the middle of the wheel and horizontally mounted Also they are not on the sable.