I am in the process of replacing al the vacuum lines in my car. Thought it might be helpful to post the physical location/routing of same.
1) Vacuum enters through drivers door hinge into drivers door.
2) master element has two lines (yellow/grn amnd ylw/red) going back through hinge area to kick pannel behind speaker.
3) The lines T from here, one set going through dash area to R side of vehicle**. The other set goes under grey channel to column btwn doors and into back left door.
4)** the line going through the dash also T's behind speaker on right kick pannel. The T goes to the R front door through the hinge area. The other line goes to the back right door and yet another T goes to the trunk area along the channel at the door sill uder the back seat and alon the right side of trunk.
I found most of my leaks at the hinge areas but in the process of repairing... I broke more lines as it was brittle. I decided to replace all the lines.
Two things not mentioned in the MB manual:
Vacuum to cruise control actuator
Vacuum to diesel stop on ignition switch, two lines
if either of these are off or bad your engine will not shut off