I have leaking hydraulic cylenders on my older, 1977, 1200 loader. After finding a rebuild kit and figuring out a wire lock i have it apart. On the end on most cylenders is a nut that is usually removed with and impact wrench. NOT this one. It has a piece or metal the size of a nut but not multiple sided (perfectly round). It has 4 holes in the top where a spanner wrench may fit and a large hole drilled in the side. Any recommendations on how to get this unscrewed without damaging the facing? Not an experienced mechanic but never saw one without a nut.