If you're building a 6/7/9, adel clamps with nutplates or just bolts and nylocks. I had several nutplates just for this purpose on the ribs of the center tunnel, I ended up adding extra adel clamps with bolts and nylocks. Not a great pic but the best I could find, bottom of the right rib that holds the aileron trim you can see the threads/nylock holding the adel clamp and wires on the tunnel side.
