I had a bunch of trucks from Mack doing the same thing, it was all drive line problems and four had driveshafts removed and balanced by a third part shop that fixed the problems on those trucks. The others had shims installed or removed to get it right with one that had a new front axle put in to stop the problem. I don't remember if it was an eaton field rep or the Mack fried rep but it was said that the axle never should have left the plant, should have been scraped.
Never seen this crap before, all of these were on the same build date or very close to the majority of build date.
Really thought about how poorly these trucks were thrown together, the quality of components went down hill for some reason and decided next time they will get rejected instead of having to play driveline ping pong.