Transmission module for a hybrid drive unit of a vehicle, the drive unit including: an internal combustion engine provided with a crankshaft, a decoupling clutch arranged coaxially with the crankshaft and a vehicle transmission, the transmission module being configured to be interposed between the engine and the transmission and comprising: a support structure configured to be secured to the engine; a module drive housed in the support structure and comprising: a first transmission member having an axis coinciding, in use, with the axis of the crankshaft and of the decoupling clutch; a torsional vibration damper configured to connect an output member of the decoupling clutch with the first transmission member; at least a second transmission member adapted to be connected to an electric machine; a transmission element connecting at least the said first and second transmission members (20, 23); said damper comprising an actuator provided with a hub, a disc coaxial with the hub and adapted to be coupled to the first transmission member by elastic means and a shaft extending from one side of the hub in use facing the engine, characterized in that the shaft comprises an end portion configured to define a centering with respect to the crankshaft and a splined portion for coupling with a disc of the decoupling clutch rotationally fixed and axially sliding, the hub defining a seat for a bearing supporting the support structure and, on a side facing in use the vehicle transmission, a centering for a transmission member. an internal combustion engine provided with a crankshaft, a decoupling clutch arranged coaxially with the crankshaft and a vehicle transmission, the transmission module being configured to be interposed between the engine and the transmission and comprising: a support structure configured to be secured to the engine; a module drive housed in the support structure and comprising: a first transmission member having an axis coinciding, in use, with the axis of the crankshaft and of the decoupling clutch; a torsional vibration damper configured to connect an output member of the decoupling clutch with the first transmission member; at least a second transmission member adapted to be connected to an electric machine; a transmission element connecting at least the said first and second transmission members (20, 23); said damper comprising an actuator provided with a hub, a disc coaxial with the hub and adapted to be coupled to the first transmission member by elastic means and a shaft extending from one side of the hub in use facing the engine, characterized in that the shaft comprises an end portion configured to define a centering with respect to the crankshaft and a splined portion for coupling with a disc of the decoupling clutch rotationally fixed and axially sliding, the hub defining a seat for a bearing supporting the support structure and, on a side facing in use the vehicle transmission, a centering for a transmission member. a support structure configured to be secured to the engine; a module drive housed in the support structure and comprising: a first transmission member having an axis coinciding, in use, with the axis of the crankshaft and of the decoupling clutch; a torsional vibration damper configured to connect an output member of the decoupling clutch with the first transmission member; at least a second transmission member adapted to be connected to an electric machine; a transmission element connecting at least the said first and second transmission members (20, 23); said damper comprising an actuator provided with a hub, a disc coaxial with the hub and adapted to be coupled to the first transmission member by elastic means and a shaft extending from one side of the hub in use facing the engine, characterized in that the shaft comprises an end portion configured to define a centering with respect to the crankshaft and a splined portion for coupling with a disc of the decoupling clutch rotationally fixed and axially sliding, the hub defining a seat for a bearing supporting the support structure and, on a side facing in use the vehicle transmission, a centering for a transmission member. a first transmission member having an axis coinciding, in use, with the axis of the crankshaft and of the decoupling clutch; a torsional vibration damper configured to connect an output member of the decoupling clutch with the first transmission member; at least a second transmission member adapted to be connected to an electric machine; a transmission element connecting at least the said first and second transmission members (20, 23); said damper comprising an actuator provided with a hub, a disc coaxial with the hub and adapted to be coupled to the first transmission member by elastic means and a shaft extending from one side of the hub in use facing the engine, characterized in that the shaft comprises an end portion configured to define a centering with respect to the crankshaft and a splined portion for coupling with a disc of the decoupling clutch rotationally fixed and axially sliding, the hub defining a seat for a bearing supporting the support structure and, on a side facing in use the vehicle transmission, a centering for a transmission member.