What is it?
 

I know this goes somewhere between the manifold and somewhere on the engine, but where? I do not know what it is called to look in my mighty Haynes to see where it goes. Also what does it do?

http://www.classic-audi.co.uk/forum/...pictureid=8631

Fastest method is to write down part number and put it in google.

Looks like part of the vacuum advance/retard for the distributor