So I've been having to deal with this random rattling noise coming from under my car for a while now. I know what it is, but I'm not sure what it's called or if the part is even necessary. But on the back end of the front drive shaft is a rubber thing... it's loose and that's what's causing the rattling. Well it was loose, I just found a piece of it in my driveway which explains why there was no rattling today. So anyway, what the heck is it and do I need it? Not really sure what I'm doing, I get the help of my dad for most of my car issues but he's just as stumped as I am. Thanks in advance!