A combine header comprising a header frame and a driveline for driving a reciprocating movement of a set of knives mounted at the front of the header, the driveline comprising: - a transverse drive shaft at the back of the header, - a bevel gearbox having an inlet axle that is rotatably coupled to the transverse drive shaft, and an outlet axle, - a lateral drive shaft arranged laterally with respect to the header frame, the lateral drive shaft having a first end and a second end, - a transmission having an inlet axle and an outlet axle, said outlet axle being coupled to the set of knives, and wherein: - the lateral drive shaft is coupled at its first end to the outlet axle of the bevel gearbox via a first universal joint, - the lateral drive shaft is coupled at its second end to the inlet axle of the transmission via a second universal joint, - the driveline comprises a flywheel that is rotatable about a central rotation axis and integral with or fixed to the inlet axle of the transmission, wherein the flywheel is an axisymmetric body with respect to said central rotation axis, the flywheel being configured to stabilize the rotation of the lateral drive shaft, - the second universal joint comprises a first fork attached to the lateral drive shaft, a second fork oriented orthogonally with respect to the first fork and attached to the inlet axle of the transmission and a cross-piece, wherein the forks are pivotable relative to the legs of the cross-piece, characterised in that the second fork is attached to the inlet axle of the transmission by being integral with or fixed to a flange (43,51) that is removably attached to a surface of the flywheel that faces the lateral drive shaft, and wherein said flange (43,51) is also an axisymmetric body with respect to the rotation axis of the flywheel, so that the flange is configured to contribute to the stabilizing function of the flywheel when the flange is attached to said surface. - a transverse drive shaft at the back of the header, - a bevel gearbox having an inlet axle that is rotatably coupled to the transverse drive shaft, and an outlet axle, - a lateral drive shaft arranged laterally with respect to the header frame, the lateral drive shaft having a first end and a second end, - a transmission having an inlet axle and an outlet axle, said outlet axle being coupled to the set of knives, - the lateral drive shaft is coupled at its first end to the outlet axle of the bevel gearbox via a first universal joint, - the lateral drive shaft is coupled at its second end to the inlet axle of the transmission via a second universal joint, - the driveline comprises a flywheel that is rotatable about a central rotation axis and integral with or fixed to the inlet axle of the transmission, wherein the flywheel is an axisymmetric body with respect to said central rotation axis, the flywheel being configured to stabilize the rotation of the lateral drive shaft, - the second universal joint comprises a first fork attached to the lateral drive shaft, a second fork oriented orthogonally with respect to the first fork and attached to the inlet axle of the transmission and a cross-piece, wherein the forks are pivotable relative to the legs of the cross-piece,