I run an old Terios (2003) for work , it has started making a horrible clunking noise from the front diff, I've had it on axle stands listening to it and trying to fathom out whats what, with the back end lifted and the front on the ground there's no drive to the front wheels unless I turn on the centre diff lock switch ... does this mean I need to source a new diff or could it be something else on the drive line any help greatly appreciated .

Thanks
Jerry