"Regarding new aircraft, delivery of the 27 new 767-300F 767s will begin with three planes in fiscal 2014, followed by six per year in 2015 through 2018. They replace aging MD10s, which have 30% less fuel efficiency.

Delivery of the 777s will be delayed slightly. Instead of adding six new aircraft in fiscal 2013, FedEx will add four. Instead of seven in 2014, FedEx will add two. Additional delays are projected for 2015 through 2018."
From this story: FedEx Beats Estimates, Orders 27 Boeing 767s - TheStreet