My guess these will all be ex Midwest aircraft 

Under a multi-year arrangement, MexicanaClick will begin receiving the 717s from Boeing Capital Corporation in March, making Mexicana the first North American 717 operator outside the U.S. Boeing Capital is the world's largest lease provider of the modern, fuel-efficient twin jet.

In addition to the airplanes, Boeing through its Commercial Aviation Services group will provide training for flight crew, cabin crew and maintenance staff as well as spare parts provisioning. In total this approach represents a comprehensive Boeing solution to Mexicana Group's fleet renewal needs.

Source Boeing.com