A fellow poolie friend recommended a great website for the FEX written:

Sheppard Air Flight Test 4.0 Prep Software ATP, Flight Engineer, Mil Comp - FAA Airline Transport Pilot

Way, way worth the $75. They will give you a sweet gouge that'll reduce your study time down by many hours. I am 100% satisfied with my score thanks to that software

I took my first FEX written years ago through All ATP's, same outcome, however I had to spend the whole day there instead of studying from my own laptop when I chose to do it.

However, if I remember correctly, the FedEx pilot recruitment website states that the FEX written is required "prior to being hired", not necessarily a requirement for the interview... Can't hurt though. I know I had it ready for the interview.

Good luck.