Mike; Just a false center rib that hangs way down and notched into the front bulkhead. There is not a whole lot of windshield heighth and of course the bulkhead is doubled with thirtysecond ply. The spars fit too loosly and needs both shimmed. I used ply to give a snug sliding fit. Originally the rubber bands kept the wings from moving up and down. Personally I think in this day and age the designer should have made it bolt on from the start. It IS a nice cheap plane tho. It looks like you are doing fine......