All the recurring talk of the infamous "53" failures has prompted me to inquire of the members: at what mileage did your block leak? Mine went at 17,000 miles. Mods: VA box. Load: Popup camper for 5,000 miles prior to failure. If I owned Cummins I would swap out everyone of these blocks up to 100,000 miles if they leaked just so I could sleep at night. This replacement would only pertain to cracks in the known castings. Other problems due to bombings would be the owners' responsibility. Fair enough? Dream on.