wheel bearing or rear end?

My 95 mark viii started with a minor metallic almost disc grinding sound from the right rear, I did the brakes and still the noise would come and go, especially when turning left. Then over time it progressively got louder, now it sounds and feels (some clunking) like the wheel is going to fall off or something, the faster I drive the worse it sounds. Anyhow, do you guys know if this is probably just the wheel bearing/hub, or could it be my rear diff? I'm not sure.

Thanks