1992 Toyota Celica noise in rear shock assembly

When driving slow I hear a knocking noise over every bump. Smooth roads create no noise. My son was in the back and we have determined the noise is coming from the suspension support off the damper shaft. Is there an easy fix or do I need to buy a repair kit. The car has 220,000, still runs good but the noise drives a person crazy. Any ideas on a cheap fix?

Check and see if muffler mounts are worn out. Could be a banging muffler. Push up and down on rear bumper see if it makes noise?

I will check that in the morning. Thanks!