These came off a 5.9 Magnum that will be getting a set of RHS heads for my project. They are a reman head, mileage uncertain as I'm not sure when in the 78,000 mile life of the truck they were installed. With 2.0 reading glasses and a magnifying glass I was able to detect cracks between the valves of cylinders 1 & 2. I was able to feel them with the sharp edge of a razor as well. Of course there could be other cracks I could not see. Apparently these cracks do not alwayse affect performance. This engine was reported to be running perfectly before the truck was rolled. It seems likely a lot of the Magnums in operation have these cracks. I put the post up to get a feel for whether I should bother to list them for sale or trash them. It's also just an interesting discussion about the cracked head issue. One of the pics that's not in good focus happens to show a crack by some fluke of lighting. In the close up, its there in the middle, might be hard to see (use the eye of faith Also interesting, the reman was done in a Cummins plant in Canada.