I have a 83 300SD,

1. The valve inline with the brake booster is a check valve with orifice, I do not know where the large clear line that exits the top of the check valve goes to ( my manual is missing at the moment )

2. The vacuum nipple closest to the check valve should have a "T" split, the brown line goes to one side and the red with blue stripe goes to the other.

3. The vacuum nipple furthest from the check valve is for the clear ( white ) line which feeds back towards the engine compartment and tee's to the vacuum switch on top of the valve cover and the other side of the tee goes to the vacuum system damper.

I do not know if your vacuum line schematic label is still intact, when you open the hood it is just to the left of the radiator and above the left headlight, its nice to have in a pinch.