If the ride is unaffected, then it might not be shocks.
How are you tires wearing? A previous vehicle of mine would make an audible metal on metal noise and it was worn ball joints.
Have you checked the suspension (linkage bolts, control arm bolts, etc) for anything that might be loose? It could be a number of things, and worn bushings could also be on that list.
Honestly, hard to say with 100% certainty without being there.