just installed new audio system in my 240 and theirs a really bad rattling sound coming from the back right side panel and i dont know how to get it off, also im about to install the front strut bar and i need a good list of name brand one's for a good price.

Are you serious?

Okay, I'll try to be helpful instead of calling you all kinds of names and inviting people to flame you.

If I had to guess, I'd say you probably broke one of your clips when you removed the panel, and it's stuck in there loose somewhere. Take it apart, then turn the stereo on and look for it. Put piece back on one by one until the rattle starts again, and you'll know the noise is from whatever you just put back on.