Vacuum line
 

I have a 87 300D, and wanted to know if anyone knows where the 1/4" hard black plastic vacuum line terminates under the dash? It starts out under the air cleaner and goes thru the firewall near the brake booster. Any help would be appreciated.

I think it goes to you heater flaps or to the vacuum pump in the rear of the car.

Forced thank you , as i have been searching high and low on the computer to try and help this chap out . Glad you showed up .I thought it might be for the economy guage but this is not fitted on the diesel .

vacuum line
 

Thank you for the answer, The green striped line runs the heater flaps, and the white runs the lock system. I was having problems with the heater/A/C system, and suspected a bad vacuum, but have traced it to the 7 solenoid vacuum strip. :D