We are moving to Harken equipment and upgrading the dual deck organizers to Harken quads. The original deck organizers has two bolts in the middle while the four Harken bolts are at the corners. I was able to Mount the quads in the same spot and drill and tap into the apparent aluminum plate embedded in the deck. I used an mechanical pencil with the lead pulled out 2+ inches to mark where I should drill the anchor holes.