Fuel pump housing. You used to be able to get them new, but I don't see them listed on German Auto Parts anymore. Search around the internet, you may be able to find a new one, otherwise you will have to search junkyards and classifieds of people parting out a 16V. You need the early 16V housing, the fuel pumps on the later ones were larger.
Originally Posted by JacksSenseOfRejection
Here's a fun fact: if someone is hitting you with a metal pipe, stay down.