i know when the rear lca bushings get old, they start making noise. i heard that noise and i even thought it was coming from inside the car. it turned out that it was just the bushings. you can try to take some oil and put it on the bushings and see if the noise is still there. i did this and the noise went away for a week or so. this is not a fix, but i knew that it was the bushings making the noise since they did not squeek after the oil was on them.

 

The rear springs tend to squeak on their bottom perches. Put some grease right there and it will stop.