I have a 2000 V70 XC AWD with 108,000 on the odometer. My mechanic has advised me that I need to replace my front differential. ( There is a faint whining noise when driving). He claims the fluid was pretty low and he could smell the damage. He did say he put a magnet in the fill hole and there were no metal pieces. I do not dispute that the differential is the source of the noise. Does anyone have any experience with this particular problem? Are there parts available to rebuild the differential? He had advised me to buy a used one that will take about a week to get here at a cost of $900. I'm sure that is much cheaper than a dealer part. I am told that the 2000 model front differential is entirely different from the 1999 and 2001, so I have to have a 2000. I'm just wondering why we aren't talking about a rebuild as opposed to replacing it with a used part that may not last very long?

Any advice or help would be greatly appreciated.