Abstract: A block adapted to be joined to a manifold for a heat exchanger by brazing or an equivalent method includes a block body having a protrusion. The block body has an engagement surface to be deployed in cooperation with the outer surface of the manifold. The protrusion extends from the engagement surface, and includes a neck and a flange extending from the neck. The flange is sized so as to be inserted through a locating aperture in the manifold. The neck is sized so as to define an annular space between the neck and the aperture when the flange is inserted through the aperture. The block body is peripherally movable with respect to the manifold toward a secured position, after insertion. The flange engages the inner surface of the manifold and secures the block to the manifold in the secured position prior to joining the block thereto.