A heat exchanger comprising: a rectangular shaped core having a plurality of fluid passages extending therethrough in a width direction and air fins interleaved between said fluid passages; tank end caps arranged at each of four corners of the rectangular shaped core; a first extruded tank section arranged at a first end of the core in the width direction, the first extruded tank section extending between and joined to a first and second one of the tank end caps; and a second extruded tank section arranged at a second end of the core in the width direction opposite the first end, the second extruded tank section extending between and joined to a third and fourth one of the tank end caps, wherein the first extruded tank section and first and second tank end caps together define a first fluid manifold and the second extruded tank section and third and fourth tank end caps together define a second fluid manifold, the plurality of fluid passages providing for fluid communication between the first and second fluid manifolds; characterised in that the first extruded tank section includes an interior cylindrical surface that extends in a length direction of the first extruded tank section to a first end face and an opposite second end face to define semi-circular openings in the first and second end faces and wherein the first and second tank end caps each include an interior cylindrical surface that extends to a cap face defining a semi-circular edge, wherein the semi-circular edge of the first tank end cap is aligned with the semi-circular opening of the first end face and the semi-circular edge of the second tank end cap is aligned with the semi-circular opening of the second end face to form a tank; wherein the cap face of the first tank end cap engages the first end face and the cap face of the second tank end cap engages the second end face; and wherein each of the first tank end cap and the second tank end cap includes a semi-circular tapered edge, wherein the semi-circular tapered edges extend away from the end faces of the first extruded tank section to provide a gap between the end faces of the first extruded tank section and the first and second tank end caps. a rectangular shaped core having a plurality of fluid passages extending therethrough in a width direction and air fins interleaved between said fluid passages; tank end caps arranged at each of four corners of the rectangular shaped core; a first extruded tank section arranged at a first end of the core in the width direction, the first extruded tank section extending between and joined to a first and second one of the tank end caps; and a second extruded tank section arranged at a second end of the core in the width direction opposite the first end, the second extruded tank section extending between and joined to a third and fourth one of the tank end caps, wherein the first extruded tank section and first and second tank end caps together define a first fluid manifold and the second extruded tank section and third and fourth tank end caps together define a second fluid manifold, the plurality of fluid passages providing for fluid communication between the first and second fluid manifolds; characterised in that the first extruded tank section includes an interior cylindrical surface that extends in a length direction of the first extruded tank section to a first end face and an opposite second end face to define semi-circular openings in the first and second end faces and wherein the first and second tank end caps each include an interior cylindrical surface that extends to a cap face defining a semi-circular edge, wherein the semi-circular edge of the first tank end cap is aligned with the semi-circular opening of the first end face and the semi-circular edge of the second tank end cap is aligned with the semi-circular opening of the second end face to form a tank; wherein the cap face of the first tank end cap engages the first end face and the cap face of the second tank end cap engages the second end face; and wherein each of the first tank end cap and the second tank end cap includes a semi-circular tapered edge, wherein the semi-circular tapered edges extend away from the end faces of the first extruded tank section to provide a gap between the end faces of the first extruded tank section and the first and second tank end caps.