A heat exchanger heat transfer element basket assembly (500) for receiving heat transfer element plates (850) therein. The heat exchanger heat transfer element basket assembly (500) includes first and second one-piece side straps (520a, 520b), a pair of inboard corner flanges (528a, 528b), an I-shaped splitter plate (530), a pair of outboard corner flanges (522a, 522b), first and second end straps (526a, 526b), and a cap. Each of the first and second one-piece side straps (520a, 520b) includes a center portion (625), a first extension (630), and a second extension (635). Each of the first and second extensions (630, 635) includes a flange portion that is folded over across the heat transfer element plates (850) so as to be operative to retain the heat transfer element plates (850) in the heat exchanger heat transfer element basket assembly (500).