Thanks ... it's most definitely the pedal assembly, no question about that. I've squirted WD40 and various other lubricants at both that upper pivot (can't get to it real well) and the area where the master cylinder plunger meets the pedal (a little better access) with limited success at the latter location only ... for awhile, I was able to temporarily make the noise go away by spraying at that plunger, but lately it's no help, and the downside is that the truck interior smells of WD40 for a few days.
I look forward to hearing any information you can glean out of GM, they *must* have a clue about this issue as common as it is, you'd think they'd come up with something.