If there is a knocking sound coming from the rear of the vehicle, check through the following:

Check tray

Check rear tray hinge points. Ensure that all bolts are tight and secure.

Check if the tray is latched closed correctly. 

If loose, retighten bolts.

Check shock absorbers

Check shock absorbers spherical bearings.

Check the shock mounting bolts and ensure they are tight. 

Check shocks for any signs of oil leaks.

Repair as required

Check final drives

Check the inner and outer final drive mounting bearings for damage or excessive play.

Check exhaust

Check exhaust mounting brackets - ensure they are tight and secure.

Check rear wheels and tyres

        Checked for play in the rear wheel hub and disk.

Check rear wheels for tightness