For those that might be hitting this problem now, I purchased just the bushings for under $100 from 1A Auto website, and had my local shop install them for about $800. I had this problem at about 100K, fixed the handling and rattling issues under the hood, that lasted until about 146k, and now I am replacing them again (only two went bad but I'm doing the whole set). This is the only real problem my LS has had so I'm still happy with it...
Also, 1A Auto has a limited lifetime warranty so they replaced the parts for free...