Front diff or transfer case

[aaron_2000]

About to change my front diff on my Range Rover but I'm still not 100% sure. The car was whining before it failed, then a massive bang followed by the front wheels locking up. Rear wheels spin fine, front wont spin at all. Gearbox still operates fine and the transfer box is still selecting range as it should, not had a chance to drop the prop yet. Surely if the transfer case had failed it wouldn't be selecting range?