Are they repairable? Did you try a heat exchanger shop?
If they are salt water aftercoolers, that might be a modern record. NY Waterway in Weehawken went thru HUNDREDS of aftercoolers on their 3406's. They had an engine with 54 hours on them that blew up from salt water intrusion. Now CAT has come up with a heat exchanger section for the aftercooler.