The payload includes a mission data unit designed to connect atomic clocks, radiation-hardened processors and transmitters for signal generation, Harris said Thursday.
Lockheed has integrated Harris-built navigation systems on five GPS III satellites, with the first space vehicle slated for a December launch.
The Air Force expects the second spacecraft to lift off in 2019. The third and fourth vehicles have completed the assembly phase and currently undergo environmental tests.
According to Harris, system testing of the fifth satellite is scheduled to start later this year.
USAF awarded Lockheed a potential $7.2B contract last month to manufacture an additional 22 satellites for the GPS III Follow-On program.