I would interested in hearing on this too - my 2000 V40 1.9 D has also started manifesting similar behaviour, which has become progressively worse. At certain frequencies/vibrations, the gear box seems to emit a whining/ringing sound. At first it only happened in 1st and 2nd gear, usually when taking the foot off the accelerator somewhat, but now also in 3rd and 4th. Funny thing is, it only starts doing it after driving for 15 minutes or more. If I do a quick run to the shops, there are no such sounds....