I currently have a pretty loud whining noise coming from the back of my car I am pretty sure it is my rear diff. I tried flushing it and it still made the noise. Any suggestions on what I should do? I am trying to avoid buying a whole new rear diff but if I have too i will. It is a 01 with 123k on it.

 

What fluid did you put in it?

Try 75/140w. Its what ive run for several years, highly recommended for higher mileage and general better protection for any mileage rear end. It may buy you some more time.