Looks like the B757 made it into revenue rotation:
flightaware.com/live/flight/FDX1525
News to me…I just work there 
I had heard it came through yesterday morning…didn’t know they had replaced the B727 on that route.
It is official, the 75 is on that run. We will begin to see it on p.m. shift beginning July 28.
1st Rev flight to DCA was this past Sat. 7/26 flt 1557 MEM-DCA.
This morning flt. 2557 repo to IAD for pm dep. ( I forget the flight number sorry 
)
Looks like it may be 1525 back to KMEM, according to history.
flightaware.com/live/flight/FDX1357
She went out heavy. No issues!!! Good times
Ahh the beauty of the 757. Max gross takeoff? You wouldn’t know it just by watching it 8) I’m still disappointed they ended production.
they stopped production because it was so successful that there was a ton built and thus a very liquid used market and built so well that they didn’t need a new and improved version (it already had very efficient engines, a full glass cockpit, and outstanding range).