Here is why my U bolts were loose. Large chuck holes in I40 Eastbound from I40 intersection with Arizona 95 to Kingman in 2011.
Lippert did step up and replace the axle in quick time. I was impressed with the service.
My U bolts are long enough that I double nut them. It will not prevent what happened to me but I have read several postings like this one complaining of loose U bolts.