Bit of a problem today. On a short 6 mile journey, stopped at some traffic lights, went to move off at green and clunk followed by a whirring sound and we were not moving.
Tried every gear, in hi/lo with locked diff and still no drive just same noise. Handbrake (which is normally quite effective) did not work, so called the RAC to get us out of the 5 lane junction.
When we got home safely i got the helpful chap to have a look underneath while I tried her in drive again. He said the front prop was not turning, but the rear was but I had no drive at all.

Last year I had a reconditioned G suffix gear box put on with new clutch so I'm doubtful it's the gearbox. Possibly the transfer box, centre diff or rear diff. Any ideas?
Not gonna get round to checking for lumpy oils in the suspected areas until Sunday so thought I put it out there for some good ideas.
Also may need a tow soon

Cheers in advance for any help!

loss of hand brake would lead you to think rear axle has a bust half shaft or other as would spinning prop,though it would seem diff lock doesnt engage

Yep. Diff lock should make it drive if it's a busted diff or half shaft. If you tried it then maybe your diff lock isn't engaging.

Definitely sounds like more than one problem. If difflock works, then even if one axle breaks the other should be OK. However, if difflock works and you have a broken shaft at both ends then it won't go anywhere.

It might be worth getting someone who knows to look at it with you, whereabouts are you?

I'd start by putting it in centre difflock, (cdl) no handbrake, in neutral. If cdl is on and three wheels are on the ground then a lifted wheel shouldn't spin far, just an amount to take up slack in the drivetrain. So, lift (Jack up) a single rear wheel and spin it. If it spins relatively freely then a half shaft/diff could be broke or the cdl .. get someone or yourself, to look under and whilst spinning the wheel, check that the prop turns. If the prop turns it points to the cdl being broke. If the prop doesn't turn it could be a halfshaft or the axle diff. Put the wheel down and do the opposite wheel in the same manner. Similarly at the front ...