707, 727, and 737 all share the same “41 section”. The 757 and 767 also share a common 41 section but don’t have any commonality with the earlier models. The latter two were designed at the same time, with Boeing using some risk management strategies: They used “new fangled computers” to aid in the design of the 57 wing, and the old way for the 67. The 57 wing turned out much better than predicted.