I have seen several airlines operating the Boeing 747-300 but with other GE engines, at least they look different, more like the ones used on the Boeing 747-400 (see photoid). So my question is are these engines "new" or are they upgraded engines? What is the difference between these two different types of GE engines?
Photo © Jonathan Rankin
Photo © Carlos A. Morillo Doria
Photo © K.H. Ng