BD’s replacement Heavy Duty EGR Coolers for the 2003-2007 6.0L Ford Power Stroke Diesels use TIG welded 304L stainless 0.375 in. O.D. x 0.048 in. walled tubes to replace the OEM inner cores that have been known to fail due to weak brazed joints. The failure of the OEM units has caused coolant to leak into the cylinders creating a hydrolock condition which will damage the head gaskets and possibly the heads themselves.