"So much for Mopar quality."

"It's the axle retaining clip..."

Wrong. The Dodge dually uses a Dana 70 differential and axle assembly.
Did you ever see one? It's a really huge mofo with a 10-1/2" diameter
ring gear. Most truck manufacturers spec it on 5-ton trucks, while
Mopar uses it on a one-ton. And it definitely does not use an axle
retaining clip like smaller differentials sometimes do. It uses two
locking axle retaining nuts on each axle with an indexed lockwasher
between them to keep them from loosening, the same as a standard
headset does. If that one loosened, then somebody didn't lock the
retaining nuts.

"Surprising, it's usually the electrical system that fails on Dodge
trucks."

Chrysler electrical systems are no worse than any other brand. And at
least they never tried "green" insulation on their wiring harnesses
like some of the European manufacturers did.

You self-professed Mopar experts have been reading Consumer"s Reports
too much.