Check the front spring shackle.
The end up inside the frame seems to be the one that wears the most.

I had this clunk when I hit a pothole that I looked for for a year or so, never could find it.
I replaced my springs and shackles last summer.
When I pulled the front shakle out of the frame I found the clunk, the top bushing was gone on both sides.
The new springs had an extra leaf in them.
The shackle did more to raise the front of the truck than the extra leaf did.
Also the negative camber was reduced considerably since the front end sat higher.