Aerolineas Argentinas converts B737-800 NG order to B737-800 MAX

Aerolineas Argentinas originally ordered for 20 Next-Generation B737-800 aircrafts, 11 of which are exchanged for the newer and more fuel efficient B737-800 MAX. The first three B737-800 NG are expected to be delivered between October and November this year and the first 737 MAX in 2017. Source