Black Vacuum "Box" ? [88 90Q]

[Matt Evans]

THere's a big black tall box that has a couple opf vacuum lines running to it.
its on the drivers side of the engine bay, next to the power steering
resivoir and infront of the coolant expansion tank.  yo have to remove it
to get hte PS resivour out.  You have to remove a couple vacuum lines from it
to do this.  

If you're like me, working in Fargo in -4F ambient, you broke one of the 
vacuum barbs off of this thing.  

So, - what does this do ?  What attaches to it ?  What no longer works, given
that i just broke it ? :)

(PS: do the power steering hoses leak through their membranes ?  what about
at connectino points ?  2 hose inlets AND the cap of my PS resivoir leak.
how is that possible ?  )