I found a black vacuum line that comes out of the little white plastic box on the top rear of the injection pump. (I think it's the shift modulator).
The other end is near a rubber fitting coming out of the firewall. That fitting has an open on it.
I wasn't sure if a black (tranny?) line should be going inside the car. Any help?
BTW,it's my 85 300D.
84 300SD (sold)