There are 2 usual noises from the gearbox.
1) Idle Chatter
Normally only when warm, in neutral and idling it will "chatter"
Not release bearing, pretty normal for our boxes (I know I've changed both release and spigot bearings to rid of this)
2) 3000rpm rumble
Sounds like looks metal in the gearbox, sorta like metal on metal grinding away.
Most noticible with a solid flywheel but still members with factory flywheel with this noise.
Loudest when engine braking in 2/3/4th gears from about 3500rpm to 3000rpm.
Also completely normal for our gearbox