2700i gearbox noise

[GTO]

My 02 2700i 4x4 DC with 303000km started making a noise late last year.

I noticed it on the way back from a camping trip, the noise is like a slight Grrrr sound and only seems to noticeable above 2500rpm in 3rd, 4th and 5th gears and more so in 3rd.
Also around town it doesn't seem to be noticeable with short trips but is noticeable on longer ones.(probably when oil is hot?)
Also with the radio on or on a gravel road it cannot be heard.
If I disengage the clutch it disappears so hence why I think it is gearbox related.
I did have the input shaft bearing changed in 2011 (198000km) but when the bearing was the issue it could be heard outside of bakkie when idling and the clutch was engaged not so this time.

I was tempted to maybe add an additive but from what I know most of them are snake oil?

Any ideas?

[Mud Dog]

From the sound of it I think you're correct in your assumption that it's box related. I'm not a gearbox fundi but it could be a cluster shaft bearing that's getting a bit noisy as the mileage is climbing.

I wouldn't be too concerned about it right now unless it's irritating you to the point where you just have to get it seen to, but I would also make a plan to get past a reputable gearbox specialist at some point in the near future to get his professional opinion.