the gearbox of the engine was moved from the bottom of the engine to the side. the gearbox makes the engine look a bit like a triangle. since the engine is close to the ground, it is possible that they can be damaged by things lying on the ground. the cfm56-7 engine on the 737 next generation burns even less fuel than the engines on the 737 classics. the boeing 737 max aircraft will have cfm international leap-1b engines. these engines are supposed to burn 10-12% less fuel than the cfm56-7b engines on the 737 next generation family.