"the NG, which had to use these weird flattened turbofan nacelles in order to get enough ground clearance" I believe your picture actually shows the 737-300 (C

"the NG, which had to use these weird flattened turbofan nacelles in order to get enough ground clearance" I believe your picture actually shows the 737-300 (Classic), which had a very obvious flat-spot in it's nacelles. The NGs do also have a slight "flat spot", but it's much less obvious.