What is this thing on a FDX MD11 (MD10?)? I assume something forward looking; not sure why there and how they got this to play nicely with radar
It's the infrared sensor for the Enhanced Flight Vision System (EFVS).
From FedEx Newsroom June 23, 2008:

FedEx Express is the first major commercial carrier in the airline
industry to receive a Supplemental Type Certificate from the FAA for
the advanced system, authorizing its installation in the company’s
fleet of Boeing MD-10 freighters. The company’s goal for the system is
to improve the level of flight safety by increasing visibility of
pilots during adverse weather conditions and darkness.
A unique application of Honeywell International “Head Up Display”
(HUD) technology combined with infrared “Enhanced Flight Vision
System” (EFVS) technology of Elbit Systems of America Commercial
Aviation-Kollsman Business Unit, positions the system as the leader in
the avionic visual technologies market.
The Honeywell HUD interfaces with aircraft navigational and flight
data systems in presenting a high resolution liquid crystal display of
critical flight guidance information. This is overlaid with real-time
EFVS infrared video of the outside world that is displayed in an
overhead unit in the captain’s forward field of view using
state-of-the-art HUD “combiner” technology. Elbit Systems Ltd.,
Electro-Optics-Elop manufactures the combiner glass.

The combined image appears like this:

Source: FedEx