I,m having transmission issues as well on my 1987 300D. This morning leaving home and climbing a hill I heard a clunk and the car would not pull so I coasted to a safe place to park. The car will not engage in Reverse nor any forward gear. When trying to place it in Park I hear a grinding noise and it appears the car is really not engage into Park so I chalked it with blocks to keep it from rolling. I hearing it could be flex discs... Any suggestions are helpful.