Gear Box / Transfer Box Strange Noise

Started a thread on this in the welcome part But since then have had a look at things.

My Disco 2 TD5 2002 Manual started making a noise then it juddered to a holt and ABS light was on.
Did this a few times just at low speed. felt like brakes where on. Got a tow home with engine on out of gear and noise was there but didn't judder to holt.
Noise seems to come from dash/gearbox and doesn't change when clutch is pressed/released or with engine speed when out of gear.
It make the noise at even very low speed in forward but not reverse.

At first thought it was prop shafts or handbrake but today tried something I should have done at first.
I put the HNL into N and put in gear and there it was so must be Gearbox or Transfer box, Yes?

It's a sort of hollow rubbing/grating noise.
When in High it does it only in forward but in Low sounds band in reverse.

Any ideas and guesstimates on prices for different scenarios?

drain some oil out of each starting with t/box

I'm willing to try anything but apart from the obvious of finding teeth bearings etc what is the theory behind this?
I wanted to top up the Transfer Box but how awkward where the filler is behind handbrake housing and cable.

I had simular sound and as it was intermittent to start with wasn't sure ended up being wheel bearing so changed front wheel hub got to do a rear one next as it's got a crack in abs ring and it sometimes throws up the 3 amigo's but I reset as required.