2005 Caravan- 107k miles. I have a squeaking noise that seems to be coming from somewhere in the rear suspension. I don't know much about suspension so I'm not sure where to start. We can hear it when driving whenever we go over bumps. I tried to just push down on the bumper to see if I could duplicate the noise with the van parked but I couldn't make it squeak that way. It is most noticeable at low speeds over bumps. Any ideas what it could be?