Well, first of all, you need a spring compressor and compress the spings before taking things loose. If you don't know this, get a good mechanic to do the work. You mention Boge shocks. Those are pretty much stock, but you have a cheaper (cheap bastard??) alternative that I think is better: Bilstien Touring. They are about as soft as stock. Go to www.shox.com to find other parts. How are your fronts? If you're getting a lot of rattle, I'd change them out too. Make sure to change all your spring seats, shocks/struts mounts and in the front, the anti-sway bar end links....made a huge difference in my S70.
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon