It might amuse you to know that when we were manufacturing new P-40 fuselages there were many times that we found errors in the blueprints as they either did not quite add up dimensionally or did not match the existing original parts/ assemblies. Fixturing was made rather easier using original stuff combined with a slew of photos of the old Curtiss plant! Just using the old documentation was not enough by a long shot. Fortunately, its much better w/ the new engineering.