99 Model year transmission have 6 speeds programming is not required.

 I have replaced a few of this conductor plates an no reprogramming/coding was required  that I can remember, however  I have found many  with shifting issues and all kinds of tranny issues do to transmission fluid inside the tcm, the fluid travels thru the wires and gets in the tcm, sometimes just cleaning the tcm and fixing the issues that causes it fixes the problem. there is a bulletin regarding this. if replacement is needed make sure to use the exact part numbers on the tcm. its being a while since my last benz issue and probably forgotten a few things but I think I may be close. good luck.