300TDi Auto Gearbox - Noise

Getting a fairly loud squeal at around 2.5-3k. Sounds just like an aux belt (which it isn't). Sounds like it is coming from the gearbox/hellhousing area, although quite difficult to tell. Has a very "belty" sound to it. I have checked auto gear oil, and levels are fine (slightly high if anything)

Sometimes when warm it stops. Any ideas or experience with this problem?

when was the last time the auto box oil was changed, also its not good to be over full and did you check the level by the approve method?

how do you know its not a belt?
does it do it in any gear?
inc park and neatral?

Its not the aux belt. Yes does it in every gear.

Silly thing but all you have is clutch packs in the torque converter.

Have you tried removing aux belts both and started it failing bearing noise ie alternator can sound like further back?
Don't run to long as have no water pump running, don't drive as no power steering.

Have you been through deep puddles on or off road? Has it picked something up?

Dose it come from one side of the engine bay or the other? Or is it as strong? Thinking possible starter motor engaged and not disengageing from the ring gear and has worn the bearing or shaft it is on?
Or vacuum pump back seal going and making a squeaky noise you will see back plate move if rivets are worn

Have you tried shifting transfer box to n or low ( could it be from there)

Hope this helps