Not really my area, but we had a diesel for a long time, and I will see if I can locate the vacuum diagram. Meanwhile, here is a pointer to a very interesting article by Steve Brotherton that explains how MB uses vacuum in a diesel car (no natural vacuum) to control shifting.

Good luck

http://www.babcox.com/editorial/ic/ic20242.htm

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe