Something broken on car. (pictures included)?

DomWe

New member
Yesterday I noticed a knocking noise when braking and than when going over bumps. The sound is from the right rear wheel area.. When driving slow it's very noticeable but going faster I didn't notice it as much. I looked around and found some metal bar thing is broke. The wheel can move around forward and back now.. I have pictures here http://www.flickr.com/photos/mndomino/

Can you tell me what this is? How much it would probably cost to get fixed? How much just the part is?
No. It's a 99 Grand Prix
 
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