A tank assembly comprising a tank for a heat exchanger, in particular for a motor vehicle, comprising: - a distribution body for delivering a coolant fluid into the heat exchanger; - a first opening disposed along the longitudinal direction of the distribution body, the first opening having a substantially rectangular shape for receiving a header with tubes; - a second opening disposed on the surface of the distribution body, the second opening having a circular shape; - at least one guiding means (14, 15) disposed in the vicinity of the second opening, and - a connector comprising at least one protruding portion (28, 29) cooperating with the guiding means (14, 15), the connector being configured to be assembled with the tank, wherein the guiding means (14, 15) and the protruding portion (28, 29) are configured to engage the connector with the tank in a first angular position to prevent the connector from moving in the axis of the second opening, and to disengage the connector from the tank in a second angular position in the plane delimited by the second opening, wherein the guiding means (14, 15) comprise a guide (17a, 17b, 17c, 17d) and the protruding portion (28, 29) comprise a protrusion (23a, 23b, 23c, 23d), wherein one of them is located on the tank and a second one is located on the connector, wherein the protrusion (23a, 23b, 23c, 23d) is adapted to be engaged in the guide (17a, 17b, 17c, 17d), thereby restricting movement of the connector in the axis of the second opening, wherein the guide (17a, 17b, 17c, 17d) is configured to releasably fix the connector in the first angular position, characterised in that the protruding portion (28, 29) is in a form of a winglet, the winglet being of a flatted shape and comprising a slope configured to interact with the guide (14, 15). - a distribution body for delivering a coolant fluid into the heat exchanger; - a first opening disposed along the longitudinal direction of the distribution body, the first opening having a substantially rectangular shape for receiving a header with tubes; - a second opening disposed on the surface of the distribution body, the second opening having a circular shape; - at least one guiding means (14, 15) disposed in the vicinity of the second opening, and - a connector comprising at least one protruding portion (28, 29) cooperating with the guiding means (14, 15), the connector being configured to be assembled with the tank, wherein the guiding means (14, 15) and the protruding portion (28, 29) are configured to engage the connector with the tank in a first angular position to prevent the connector from moving in the axis of the second opening, and to disengage the connector from the tank in a second angular position in the plane delimited by the second opening, wherein the guiding means (14, 15) comprise a guide (17a, 17b, 17c, 17d) and the protruding portion (28, 29) comprise a protrusion (23a, 23b, 23c, 23d), wherein one of them is located on the tank and a second one is located on the connector, wherein the protrusion (23a, 23b, 23c, 23d) is adapted to be engaged in the guide (17a, 17b, 17c, 17d), thereby restricting movement of the connector in the axis of the second opening, wherein the guide (17a, 17b, 17c, 17d) is configured to releasably fix the connector in the first angular position, characterised in that the protruding portion (28, 29) is in a form of a winglet, the winglet being of a flatted shape and comprising a slope configured to interact with the guide (14, 15).