I have struts that are still in good condition but the bushings on struts is completely torn apart and will make knocking sound when i drive over bumps. I don't want to replace the hole strut. I was wondering if some companies sell the bushing separate from the strut. The vehicle that i have is Lexus GS300 2003 2nd generation.

Here is a image that shows what bushing i am talking about.

http://imgur.com/a/Mupnt

 

That's... weird.

Anyways, I Googled shock absorber bushing and a whole bunch of results came up. You just need to find something identical to the one in your strut.

 

If your bushing is that bad, just replace the strut...it's likely due anyway.