Hi Andrew;

A friend and I just pulled the engine and tranny out of a '76 300D. I don't recall any vacumm lines, but there was a solid linkage rod on the passenger side of the engine going back to the transmission. Check out the following link for an on-line 115 manual archive.

Good luck.
Drew


http://mb.braingears.com/114_115_Disk1/program/matrix6.htm