Goosed up here
A Goose neck 12 point box-end, sometimes with a little bend in it. Getting it off is the easy part, putting it back on. Some times that takes an off-set deep box that has been worked on a little. It is old school but we used to call them shop made tools. I would use the Craftsman brand to modify the Snap-On ones cast to much. Yours. R.E.A. III #80888