Trim the barcket to the dimension indicated by the plans. Clecoe the brackets to the ribs, locate the additional two mounting holes and match drill them to #19 with the rib flange. Dimple the holes on the bracket and the rib for #8 screws. Drill the rivet holes for the platenuts. Bevel the plastic piece to fit the bracket radius. Mark the center large hole on the plastic block and drill to #40 to use as guide for match drilling with the floor pan.
