I'm sure all of the suspension clunks etc that apply to E34's hold for this one, plus the Nikasil issue. And to help get you started:
http://www.unixnerd.demon.co.uk/e31.html
If I'm reading it right, they also had self levelling suspension. Make sure this was changed out because when it fails (not IF), it's mucho $$$ to fix or to replace with non-self levelling.