Fabricated F-916C spacers. Enlarged holes in 4 F-916 seat ribs (for control column mechanics clearence). Made cut outs of 2 F-916 seat ribs for control access; drilled F-716B access plates to the cut-outs. Enlarged holes for 5/8" snap bushings in the F-915/916 seat ribs. Clecoed the 2 innermost F-916 ribs to F-976 bottom skin, F-904/905 bulkheads and marked cutouts for longintudinal 5/8" snap bushing holes.