Transmission problem?

Hi,

I have recently bought my first land rover. A 1994 300tdi defender 90 which I have taken on as a bit of a project.

Unfortunately, it seems to have a transmission problem (amongst other problems such as an oil leak, rotten bulkhead and a great big hole in the N/S chassis outrigger!)

It develops a whine in high range in 3rd, 4th and 5th gear when under load above 30mph. The whine goes when the clutch is depressed or once you come off the throttle.

I decided to try it in low range through the gears this morning and there was no whine.

Has anyone got any ideas what it might be? Could it be a problem that could be solved by something as simple as changing the oils or am I looking at getting a new gearbox/transfer box?

Cheers
Scott

check oil in t/box ,output brgs ,you can remove sump plate and check condition of gears etc,could be both but probably t/box as in low gearbox is turning as fast as in high box,but still check condition of gear box oil too