The present thesis work is developed inside the EVERGRIN project, which aim is to realize a new concept kit to convert an ICE (Internal Combustion Engine) vehicle into a full electric one. The main objective of this work are the mechanical design of the Traction subsystem which has to be mount on the old ICE vehicle. In particular, starting from the vehicle's gearbox housing scansions, it has gone to the development of the adapter plate to connect the new electric motor to the gearbox housing, up to the design of the coupler to connect the motor shaft with the primary shaft of the transmission.