http://www.pskits.com/catalog/index.php

I bought from them the set for the power steering pump for the E32 750. Works great. $ 20 vs several hundred $ for a new pump.
Here are some pics when we did it and some info how to disassemble and assemble. Although the pics are not from the 3 series it might help you
http://www.bimmerboard.com/forums/posts/535277