What's this part please?

Hi all i'm hailfrank (pete) off thelatebay.com. I've just bought a mk1 gtd but my introduction to ownership is not as smooth as i'd have liked.
Sorry this is my first post but I joined yesterday with the intention of an intro and pics etc but the vw fairy had other ideas.
So…. what is this part?



I seem to be leaking from underneath it. Is it a bolt on bolt off part, a case of a refurb or do I need to cry?
i'm off to the intro part now

Pic doesn't work mate. Sorry.

Your image link is in an area that requires logon to that forum

Ok got you. Just uploading them elsewhere.