Well, after all that, the rattle I've had since getting the Charger back from the dealer boiled down to human error. It seems the tech hand-tightened the bolts on the swaybar. So the tech at my regular service dept in Modesto was kind enough to fully tighten all the bolts AND the end-links and now there is NO rattling, thumping, thunking, crunching or any other unpleasantness when I encounter bumps in the road. The original issue was just the swaybar bushings finally wearing out after about 4 years of heavy-duty service. Thanks for all your input and suggestions!