what was that
 

so when i have he windows down and i go over a bump i hear a really aoying sould come from the driveres rear of the car. it sounds like i ran over a mouse or something.

is that something that i need to replace or is it just something that needs lubed up.

It's going to be impossible for us to tell you with that little bit of information.

yeah i know but that is like all that i have. never mind

I don't mean to sound harsh or anything but seriously I could only give shots in the dark about what it could be. There are plenty of random rattles and squecks on mustangs that just comes with age. Subframe connectors really help eliminate alot of it. As long as it doesnt sound like its comming from a suspension part, like where two things bolt together, or a shock, I wouldn't worry about it.