unknown vac line

Hey guys long time reader first time posting. Up till now ive been able to use the search to find things I need to know about my car. Yesterday I changed the starter in my 94 c280 easy enough to change. When I was finished installing it. I looked and notticed a vacuume line was unpluged. Looks like it may be for the trans. But ive been unable to locate where it goes. I traced it back to where its still pluged into the top of the intake manifold. just above where the oil dipstick is. However not knowing what the line is called makes it hard to figure out where it goes. i'll try to post up a pic of the line and where its still pluged in later today. If someone could link a vacuume diagram for the intake manifold would be great. Or if you know where the line plugs in would save me some time.