I spent 20 minutes or so upgrading the padding on my leading edge / fuel tank cradle by using foam pipe insulation. The tank fits a bit more securely now and should be better for riveting the ribs in place. Then I dimpled the left and right hand inboard tank ribs and countersunk their T-407 doubler rings. I used my squeezer to set the nut plates in place. No sealant is used because the access plate and cork gasket (if you choose to use them) will be coated with tank sealant and will cover all this rivets.