Grinding Noise From Rear... Diff? Hubs?

[tuitahi]

Got in my car to leave work this afternoon and was greeted with a lovely new sound.

Coming from the rear of the car is a loud rubbing/grinding noise on each revolution of the wheel. As you speed up it almost becomes a solid noise. It starts after the car has travelled about 10 meters and remains until it comes to a complete stop.

Not sure if I'm imagining it but I swear I could feel it a little (almost like a slight hesitation on the noise)

This happened in 1st and 2nd (haven't tried 3rd) however I couldn't notice it in reverse.

I have checked;

for anything around the wheel that may be rubbing but I can't see anything.

the backing plate is not rubbing on the disc.

Anyone have any ideas?

Hubs

Diff

anything??