i too am leaning towards bad cv. run your hands over the rubber boots and see if any cracks or grease being sprayed all over the place. try this, go to a parking lot and drive in a circle to the left and listen. if cv is bad on left side it will clunk while turning left. then do the same going right. etc. if this doesnt work, take it to repair shop and take them for a ride over small bumps and dips and see what they say. i dont know what u could grease up to make a clunk go away. good luck, rob