My undercarriage and skids etc are flawless. The Ford service dept literally said to me today “we don’t really know what caused this”. There’s no physical damage to anything. But it’s not going to be covered because the truck is modified. Simple as that.
And that attitude by some (many?) dealers is why I did not get an extended warranty. My dealership so far has been great, but it's pretty obvious I'm using mine hard and have changed many things. I don't expect to have any driveline warranty, even if it wasn't my doing.