Fonr brakes: http://www.realoem.com/bmw/showparts...69&hg=34&fg=05
Click on the pertinent link above and please tell us the part that is giving you trouble.
My guess is that it is the brake carrier, since I figure you would have known how to describe the hex bolt.
The following DIY is my favorite on E36 brakes on the entire Internet. Feel free to ask any questions not answered in that DIY: http://www.bimmerdiy.com/diy/e36brakesystem