Backdrilled the 10 1/4" bolt holes and pilot drilled the 8 wing mount bolt holes throught the doublers.
Backdrilled the 4 vertical L extrusions to the 1/4" bolt holes. Marked and drilled the positions of the A5 rivets on the L's and drilled them through the packers. Fitted them to the spar and backdrilled the rivet locations through the web. Enlarged the holes to A5.
Backdrilled the top and bottom flange holes through the doublers.