I bought my truck with what I assumed was a wheel bearing problem. At 30 a loud grumbling starts, which gets louder the faster you go. At high speeds it sounds like a helicopter is in the cab. The noise reduces significantly when curving left, so a left wheel bearing seemed like the logical diagnosis.

Today I got the wheel bearing off and there is no play in it and no obvious sign that anything is wrong with it. But behind the wheel bearing it was quite rusty and I see what looks like the disintegrated remains of what might have been a seal on the CV Axle. There was a ring that looks like it was probably once part of the seal, but it is now severed, I pulled it off axle entirely.

Does anyone know what this part is called? And do I need to replace the whole CV axle to get it?

And would the failure of this seal explain the noise I assumed was a bearing?

Here's some pictures of the failed part:

 

I took off the other side to try and get an idea of what it's supposed to look like, and the other side looks just the same. Same loose rubber ring, same tabs.