Drilled wood spacers for bolts. Assembled center section with spacers and measured spacing at 1.438". Final drilled, deburred and countersunk all holes on top plate of center assembly. Disassembled all. Drilled holes for rear seat rudder pedal brackets. Reassembled center section bulkhead assembly and installed forward control mount, seat belt attach lugs and spacers. Riveted nutplates and forward flange. Installed SB750-10 bushings in lower holes.