Would you replace or rebuild a rear diff with 160k miles on it?

Thanks

I have 157k miles on mine. It has a whine in it, and we changed oil about 2 months ago, and he said "see how long this lasts" The oscillation noise went away for a few weeks, but now I can really feel in grinding at all speeds. Will start to look for a replacement.

Bearing noises don't go away and come back. Once a bearing is damaged it does not get quiet. Maybe you should have it checked again. Does the tone change when letting go of the throttle? If the noise changes while turning left or right, it could be a wheel bearing

Thanks, we've checked, and it's not the wheel bearings or the CV's. I'll be looking for a replacement, Thanks.