check mbz.org
 

At www.mbz.org in the articles section, there are some good articles on transmission tuning that will help. Other than that, there are lots of posts here describing transmission modulators and the like, but I would start with the articles

http://www.mbz.org/info/articles/trans/adjust/

http://www.mbz.org/info/articles/trans/service/

either one should be what you want.

later

Transmission Shifting
 

I have a 1984 300D Turbo that has not been shifting as crisply as previous 300D's that I have driven. I don't believe that the transmission is bad because the car has only 94K miles on it and has been serviced from new religiously. The other thing that makes me believe it is something else is that I developed a leak in one of my vaccum lines and the car started shifting very crisply until I fixed the vaccum leak. Does anyone know of any components that need replaced or adjusted to restore the shift quality of my car. Thanks

DieselNation

While there was a vacuum leak someone probably compensated for it by turning up the modulator on the transmission. Now that the vacuum leak is gone, it is shifting really soft because full vacuum is there. Now it is time to turn down the modulator.