Tied up some loose ends prior to finishing up all of the riveting on the bottom skin. Fitted the F-904L attach strips in four places - these tie the F-704C/D center section up-rights to the longerons and F-770 side skins. Fitted the F-623A aft attach strips to the F-623 L&R and to the F-706 bulkhead to tie these parts together. Riveted F-623 L&R to the F-776 bottom skin. Riveted the nut plates to the F-715 outboard seat ribs. Had time to rivet the F-715 R to the F-776 bottom skin.