Whining noise when driving above 40-50km on TD42 GQ

Hey I have a noise which starts up around the 40-50km mark, it goes away when I depress the clutch pedal, gets less as I get faster, well just becomes a higher less audible pitch. Is it the gearbox or a bearing somewhere, any idea of price range if its a cheap fix or nasty expensive.
Much appreciated, just bought it and thought that it was wheel noise initially, and now have cottoned on to it being more. Also when I am in idle I hear that sort of bearing sound in the clutch again which I have heard in a lot of older cars, depress the clutch it goes, take it off its back again...any ideas? Cheers

Could be the throwout bearing in the clutch assy..???

X2 with Ade. last truck had it. you'll need to drop box, might think about replacing clutch at the same time. will last as you do a fund raiser.

X3 throwout bearing. If you have apart I would also be replacing the clutch if its got a few k's on it. Its also good practice to replace the rear main while your at it.

I would put it up on a hoist with someone in the vechile running it and finding exactly where the noise is before jumping in and doing the throwout bearing.
lol just read the entire post have to agree with above x4

Cheers Fullas, tax time and maybe a bonus coming up so may be able to put up the mulla which is nice timing!! hah, Clutch feels strong as, did all the usual tests and no slipping at all. heres hoping.

I would almost put money on the gearbox input shaft bearing the thrusst bearing should not be spining (if adjusted corectly) unless you are engaging the clutch, when you engage the clutch there is no longer any load on the input shaft.

Is the noise more audible with the engine running and in nuetral?

Yea bro, the noise disappears when you engage the clutch. to be honest, I went to a diesel pump mechanic and he started his GU and he had the same noise, but I would like to iron it out if possible. What are the tell tales of the input shaft bearing being busted?