Many thanks for the good description. I hit them somewhat harder than you described, but they (all 4) sound as solid as rocks, even the muffler and related pipes. I can simulate the noise by striking the upper control arm on the left wheel. But this niose IS the rotor gravel shield. I have insulated it from the lower ball joint with a rubber pad which stops the vibration but has at this time had little effect on the noise at 20, 40, and 60 MPH. I will check again, the shield is tight and has no gravel trapped.
if the noise is not gone i am now to the point of taking the truck apart a piece at a time to find this, so any suggestions will be GREATELY appreciated.

Mark