With the spinner cone notched out, I drilled holes for the mounting hardware. Using several pieces of masking tape, I attached the spinner to the back plate, then using a dial indicator I was able to spin the prop and true up the cone on the backplate. Once I got it adjusted where I wanted, I marked the hole locations in the backplate and removed the entire assembly. With the backplate in hand, I center punched each hole location and drilled. Once drilled I was able to use an anchor nut to center and mark rivet locations. With rivet locations marked I center punched and drilled those holes as well. With everything drilled and deburred, I installed the anchor nuts and reinstalled the entire assembly. Everything fit very snug, and I hope that all the extra effort results in a true running spinner.