Does anyone know what this is ive asked a few times with no real joy.

Its a 2.0 Focus, when pulling away, and crusing up to and under 2000 revs, the gearbox is making what sounds like a snoring sound, its like a dry bearing rattle, ive changed the fluid and no joy, its not the clutch release bearing either, you can hear it rattling on idle, and like i say, pull away it does it up to about 2000 revs, then stops, and then comes back again when you drop below 2000 again.