2000 Ford Taurus Rear suspension

Hi everyone. I have a 2000 Taurus wagon, with 159000 km on it. I have recently noticed a "clunking" noise when going over bumps, coming from the right rear wheel. I have jacked up the wheel and gave it a shake, and everything feels tight. I also checked the stabilizer links, etc, and everything looks OK. As it is a wagon, it has shocks on the back and not struts. I'm wondering if the shock is defective. The rear of the vehicle is not bouncy, but I don't know what else it could be.

Any suggestions would be appreciated.

Thanks!