JRJ, I also inqiured about the green and white (check valve?) months ago and haven't recieived a reply. On my 85 380 se there is also a black and blue one on a vacuum line nearby the g/w one. I asked a MB indy and he said there are so many different ways to hook them up it doesn'y really matter. I didn't believe that response, and needless to say he did not work on my car. Please let me know if you get a good answer, Thanks, Rainman