knocking sounds under jeep

I have had this problem for a long time and no fix. suspension problem when going over pot holes or the usual road bumps there is a bang sound like there is something loose under the jeep (GC 1993). Had the under carriage check by a shop. All seems OK. Rides smooth and seems to not make as much noise as the vehicle gets warm...I have checked the bushings in the shock mounts and just not finding anything wrong. Any ideas?