This is on the SS. I'm sure I had used them on an SS before, but it certainly didn't line up. Maybe the lower holes are for the ST series. Top holes worked for Minnie, where they have been used before. Definitely been on two of my bikes, and I've only owned this one SS. 888 and ST2 also had engines out, 888 and Monster should be the same. It has an aluminium spike on the other side going into the swingarm.
I also worked out the photos are cloudy because my iPhone lens was dirty.