my new replacement windows. This was so I could replace my aluminum frame windows with new ones without disturbing the stucco. I cut between the old windows and surrounding stucco with a fine kerf diamond blade and then cut through the old nailing flanges with a fine kerf carbide blade and the old windows popped right out. Without the flange the new windows fit right in and I secured them as Jason says through the window frames with fine thread self-drilling screws. This is how a masonry casement window is mounted. Before I set the new windows in, I filled the extrusion voids with strips of 1/2″ styrofoam insulation I ripped on my table saw to minimize the amount of caulking (same color as my stucco) I needed to apply. Look on Google for “casement window” for more info. Luck, Kizmet