My little truck is running great! I took it up to Spring Hill today for a Discount Tire rotation and it was the first time I've flexed her muscles since the rear-end job, and I was stunned! There was alway an engine rattle that rolled around in her straight pipe as I approached cruising speed, and having just completed a 5k+ mile cross country jaunt, I knew it well.
It is now gone. Replacing a loosy-goosy, near death rear-end with one that appears to be solid, changed everything. The new axle is of unknown heritage, has fresh fluid and it's applying way more torque back to the engine. The vehicle gods are on my side. Thank you.