1. Airfoil
The Boeing 737-300 airfoil, unlike some aircraft, does not have a NACA number. This is because the airfoil for the 737-300 is custom made by the Boeing Company. The airfoil for the 737-300 is taken from the earlier and less efficient 737-200.
The main changes to the airfoil focused on the leading edge contour and improved high-speed performance and the turbulent air penetration speed. The airfoil itself is mostly symmetrical at the root but it becomes somewhat laminar the farther down you go on the wing as shown in the airfoil cross sections below. The identifier given to the wing by Boeing for the wing root airfoil is BAC 449/450/451 and the wing tip airfoil identifier is BAC 442 mod.