Hello all, In addition to the winglets, other differences of the -400 over the -300 include an electronic cockpit, eliminating the FE; a redesigned fillet at the forward wing root; and a wing of a different airfoil section. The -400F has the winglets but no extended upper deck whilst the Japanese domestic version, the -400D, has the extended upper deck but not the winglets. Only the -400 is in production and the Japanese don't need the range-extending qualities on their short range shuttle flights. There are other variations out there but escape my recollection. Chris >Is the only difference between the 747-300 and the 747-400 the winglets? >Could a 743 be converted into a 744 with the addition of winglets?