I am hoping it is the orings. I got a spare block with it and it has cracks marked off with marker, but again only at the top between the sleeves. It has no sleeves in it and I see no cracks at the bottom. I am waiting for the tractor and the undissaembled engine to come later in the month. I will put some antifreeze in it with the pan off and see where it is dripping. Kind of interesting how these old tractors are all a little bit linked to one another. I guess that is why I never met a tractor I didn"t like!