I have a thumping/knocking sound coming from under the front end of my '96 XJ. It only does it while moving, and is definitely rotational in relation to the wheel, and not something induced by bumps in the road. No brake hardware is rubbing, etc.
So, for the big answer to "What are you fixing this weekend?", I now have two new Timken hubs and two new axle u-joints on my D30 as of yesterday (Saturday) -- AND THE NOISE IS STILL THERE! I removed the front driveshaft this morning, and the noise remains the same.