Changing alternator in D2 FL 3.7

[ainarssems]

Is there anything wrong with alternator or are you just changing it as preventative maintenance?

On our A6 brushes were worn on alternator at about 170k miles, I just changed brushes without taking alternator off as it was much easier, slip ring was still in good nick. Front end would have needed to be moved in service position to take the alternator off.

[notorious]

It is starting to whine a bit.
Also 13.6v on battery when idling, which is a bit too low.
So I thought it is time to change it preventively.