super squeaky rear suspension e320 wagon

[240dddd]

I have a 1994 w124 E320 wagon. The rear suspension is squeaking on both sides something awful. It's a constant squeaking when going down the road, and i can create it by just pushing the rear end down by hand even a little bit. However, I cannot create it once i've jacked the rear end up so I'm having trouble pinpointing where exactly the squeaking is coming from. I've replaced the sway bar links since it's easy, but that didn't make any difference. Also, the SLS system functions and doesn't leak.

Is this a common problem with the w124 rear suspension? Is there a likely piece of the rear suspension I should be checking next?