After replacing all 10 old rear bushings with poly I still had an annoying giggling sound from the rear. I had installed new Boge turbo gas clearly marked "made in Turkey" [next step in firmness above OE] about 2500 miles ago. Several of you responded who had similar experience and attributed it to the shocks. I took my Boge's back for credit and got a set of KYB GR2 which is their OE level. I reused all bolts and spacers which were the orignals from Volvo. NO MORE GIGGLING. My theory is there is something about the seal in the Boge's that caused the sound. The original sleeves have a slight amount of play around the bolt and both upper and lower mounting bolts have similar minor play inside the shock mount but apparently that was not contributing to the noise. My conclusion is it was the shock itself. I'm in a temperate place so it had nothing to do with stiffness caused by low temp. Sorry to say it was something about the Boge shocks mfg in Turkey that was the culprit. The instructions that came with the KYB's said to pump them up/down by hand before installing to get the nitrogen gas back into the resevoir which I don't recall being recommended in Boge's instructions. Maybe that contributed to the problem but it was too late - I had exchanged them by then.