Outer Limits 4x4 Board

I have a 94 model troopy with 285000 km and it has just developed a mild rattley grinding sound in 4th and 5th gear.It is more noticeable when coasting in gear and stops when the clutch is depressed so far i have put new oil in the gearbox and transfer but that didnt stop it.Does anyone have an idea what it might be and if it will last the week out so i can fix it over xmas.Thanks in advance for any help

is the noise there at idle? if so it may be your throwout bearing

There doesnt seem to be a noise at idle only seems to happen in 4th and 5th gear when driving