My 300SD always slammed into gear, and I always suspected that there was an internal problem too, especially considering it has over 300k miles. Anyway, I drove it like that for several months, then one day I was trying to get the center vent to work, and realized that the pod was shot. Not wanting to bother with the pod, I took it apart so it was always open, and plugged up the tube. After driving it I was shocked that it now shifted like butter, and the shift points were right where they are supposed to be! With as many Benz's with bad pods out there, I would say that be the first place a person should look when they have a rough shifting tranny.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head