The Needle Bearing holds the inner part of the half axle when it is all the way in, and the hub holds the outer part of it. If your needle bearing is gone it will make noises and you will not be able to figure it out until you take it all apart and look at it. I was so confused with this myself until I got it apart and saw the shape of the bearing....Now and then it made no noise...but when it did make noise it was not nice.

Check the needle bearing.