An alignment would be needed after replacing ball joints. Perhaps an adjustment was left loose and parts are shifting. The alignment can also put suspension parts into a different orientation to where they can rub or travel over previously worn spots. Upper strut mounts are a common source of that type of clunk. An inspection should reveal the source of the noise, especially if you can make it occur while standing still.
If you have to be moving to hear the noise, consider borrowing a tool called the "Chassis Ear" if you can find one at an auto parts store that borrows or rents tools. That's a set of six microphones you clip to suspect parts, a switch box, and head phones. You switch between the microphones and listen during a test drive. By moving the microphones around, you can zero in on the source of the noise. Be aware that many mechanics have never seen or heard of his tool, but most new car dealers have them.