Do you have the non-self-leveling shocks now? If you have over 30000 miles on them, it is a safe bet they are in need of replacement. New Sachs struts will likely help your sagging rear end, even if they are not self leveling. Ride and handling will be dramatically improved. I have yet to read of a successful rear shock conversion on these cars, so I doubt it is very easy, and probably involves lots of $$$$$$$$$$$