What is the device at the tail of the F-16 Block 60?
That’s a ram air intake and exhaust for a heat exchanger used to cool the Falcon Edge Integrated Electronics Warfare Suite (IEWS). The system remains fairly clandestine, but a few of its components are known to exist.

https://www.northropgrumman.com/Capabilities/FalconEdgeIEWS/Pages/default.aspx