A heat exchanger suitable for use as a condenser in an automotive air conditioning system has a pair of header tanks connected by flat extruded tubes. Air centers are sandwiched between the tubes for extracting heat from refrigerant directed through the flat extruded tubes. Each of the flat extruded tubes are located in spaced parallelism and each of the tubes have an end portion with a tapered outer surface for piloting the tube into contact with a mating tapered surface in a header opening and wherein the axial length of the end portion and the tapered surfaces are selected to define a brazed joint having maximized contact surface and strength. Each of the flat extruded tubes has a peripheral shoulder engageable either with the outboard surface of the header or with a countersunk surface portion thereof to precisely locate the end surface of each of the tube end portions with respect to avoid excessive tube stickout within the header tank volume.