Rt Wing rear spar hand rivet all but ribs. Drilled wiring gromet holes and cleaned them up for nylon/plastic gromets. Top hole is for landing and taxi lights...bottom hole is for nav lights. I accidently overdrilled (with step drill) the nav light hole on rib for bell crank. It still fit a rubber gromet perfectly, and after popping that sucker in, I was able to put the nylon/plastic one in like a perfect fit.