I had the same symptom, but I knew exactly what it was based on when and how it happened. Tightened up the front spring pack u-bolts and no more clunk/bumping while articulating/turning. These were new u-bolts when I lifted a year and a half ago, I had retorqued them after about 100 or so miles, but they still needed to be retorqued again after a couple thousand.
The sound was caused by the leaves shifting around within the packs. This may not be the cause of your sound, but it was for mine.