The rears should be relatively easy to find, at least compared to the fronts. I'd check ebay, as well as go lurk on the e36/46 boards. They can't use the rears but seem to like the fronts. You might also take a gander on bimmerforums, presuming you haven't already. Actually, I know someone who has, or at least he had, a good set of front and rear if you're interested in a complete set.
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