Good Mechanic in DFW area
The place I goto to get advice on my 300D is German European Imports here in Plano. All the mechanics there are certified MB mechanics and have been working on them for a really long time (on the wall they have one plaque from 1974). They're very honest and will explain what needs to be done, and if there are options they'll give you em.
You can reach them at (972) 422-7780. The head mechanic's name is Sam, if you want to talk with him. They are located at Ave K and Plano Parkway (1100 Summit #106 is the address on their Business card)
As far as replacing the Transmission, for my car. The Tranny costs $1800 for a rebuilt unit from the MB dealer (Ewing ********)