The last time I had a pinion bearing die I ignored it, I wanted to see how bad it would get...
When the noise became distinct enough to positively identify it it sounded rather a lot like listening to a traffic reporter reporting from a helicopter..
When it got loud enough to drown out the stereo Something needed to be done
it sounded like I was following an M1 Abrams..
at the time I was still running a 3.73s behind a 2.9 in a my truck as a 2wd
that rear is still in my truck now as a 4.0, 4x4.
there are times I wish I had time and energy to regear to 3.73's and switch from the open front and T-L rear to Lock-Right diffs at both ends... (Got both Lock rights sitting here on my desk)
but since my stroke last year I get tired real easily, as in getting out of bed and getting a cup of coffee makes me want to take a nap

In point of fact If I make the mistake of carrying my coffee in my right hand I wind up taking a shower and going back to bed...
I can do things with my right hand but I must WATCH my hand while I'm doing it.
But I'm still here...