1996 LS400, 123,000 miles - I hear thumping.

1996 LS400, 123,000 miles - I hear thumping noise from the front right side of the car only when I go over a small bump, either while turning on to my drive way (over a small lip above the road surface) or other small road humps. I have replaced both the front struts, strut mounts, lower control arm. Upper link arm. My auto mechanic could not locate the problem. Can you help diagnose the part(s) that need to be looked at for replacing them.