If there is a knocking sound coming from the rear of the vehicle, check through the following:
Check shock absorbers
Check rear tray hinge points. Ensure that all bolts are tight and secure.
If loose, retighten bolts.
Check final drives
Check shock absorbers spherical bearings.
Check shock oil levels.
Replace as required
Check exhaustCheck final drive mounting bearings for excessive play.
Check exhaust mounting brackets - ensure they are tight and secure.