Ok, I have partially fixed my vacuum trans issues on my 87 190DT. I had a vacuum leak so the trans moudulator did not get a signal. There is a white check valve in the drivers cowl. One side has one nipple the goes to vacuum, the other side has 2. One of the lines is a red w/silver plastic line. It does down by the m/c and cannot find where it goes. What ever is connects to is bad. Any ideas? I cannot find a W201 chassis vacuum diagram. I now have 6" vacuum going to the trans but now it is shifting too soft since I do not have a boost signal to the vacuum amplifier. I am trying to figure out if my VASV or switchover valve is bad.

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1987 190DT, clackity clack
90 Mustang track car
95 Lightning