A little while ago my gear box started to make a loud whining noise when I accelerate in 5th gear, so mainly on the highway. It also happens in 4th but is a lot more subtle than in 5th gear.
It almost sounds like a similar noise to straight cut gears. Obviously not that similar but there is a resemblance with how it whines.
It only happens when accelerating, even just a tiny bit makes the noise. It also gets louder the quicker the engine/gear box is spinning. As soon as I take my foot off the accelerator it stops, so doesn't make the noise when coasting in 5th.
The car is a 1998 Nissan Pulsar N15.
I can make an edit with a video of the noise soon.
Appreciate any advice