[Engine] Where does the vacuum pipe go??

[nikplume]

Hi there.
I had to take a few parts out to install some new brake pipes and (rather stupidly) I didn't take pictures of where everything went. Everything is back together now but I can't find where to the vacuum pipe that comes out of the back of the vacuum tank goes. It is the pipe on it's own that points towards the back of the engine bay. Can anyone tell me where it attaches please? I can't see it anywhere

I have a 2002 1.9D