older diesels i think were much better in water when they had mechanical fuel injection and no electronics so to speak of compared to today as long as the intake and exhaust were above water they kept on running. These new trucks are ALL electronics. electronic activated injectors and sensors everywhere and computers ETC, as soon as water gets into a few of the connectors you are done IMO... I would not think a dmax would go any deeper than say the same truck with a 6.0 in it would go, could be wrong though?????