I finally figured out what was causing the growl in the drivers front only at certain speeds.... randomly collapsing brake hose. Why it only became noticeable 45MPH and above remains a mystery to all who assisted. Ive had brake hoses collapse before and its quite noticeable at all speeds.
On a whim I swapped out the brake line on the driver side because it was about the only thing left to do, other than caliper, but the caliper "looked" and behaved as expected. Swapped the line out for a new one, no more brake growl. About a week or so after the swap, the passenger side started to growl when brakes were applied 30mph and up. Swapped its line. No more growl. Had bought a pair when doing the drivers side, wanted to see what would happen b4 doing the passenger side. Lesson re-learned, like most things that are paired or mirrored, do both at the same time, even if one side appears to be OK.
One final note, traded the Explorer off on an Expedition. Now I'm learning all the quirks of yet another Ford.