Hi, can anyone tell me what it is , that has to be changed out to convert a 717.402 into a 717.400. I know that the 717402 has an optical sensor for the speedo and the 717.400 has a mechanical drive, is it as simple as changing the drive shaft or must I replace the complete end housing of the tranny. Are there other options like modifying the dashboard speedo to accept optic or......... does anyone have the required parts ? I am hoping to fit this 5 speed to my 73 , 280 mercedes, also need the shift gate and linkages. thanks johnw