I had one of my OEM endlinks making a fairly loud clunk over bumps and imperfections in the road. There was only a tiny amount of play in the ball joint and it was almost impossible to reproduce the sound when the car was stationary. I finally figured it out while lying under the car with the suspension fully loaded and having a friend push up and down on the opposite side front quarter panel.
The noise seemed out of proportion to the small amount of slop in the joint, but it went away completely when I replaced it. Only cost me $15 CDN for a new one, so I bought two for when the other side fails.