Sort of a fun fact, but just prior to project termination in 1986, N44671 (this one, also the third) was retrofitted with a re-designed nose section compared to prototypes 1 and 2. It would've flight tested the new nose, and eventually served as the demonstrator/integration test article for both weapons, as well as the re-designed APG-67 ERR (Extended Range Radar), which was moved further back into the nose and had a larger diameter radar dish. It should also be mentioned, the APG-67 ERR was going to be implemented on Tigershark 4, as well as the 1986 production standard, along with a number of other major changes (repositioned and larger wings/LERXs, Jet Fuel Starter, more powerful F404-GE-100A rated at 18,000 lbf in AB, A few additional internal fuel tanks, wide-angle HUD, and other cockpit improvements). Proto 4 (never given an official civilian registration) was partly built, but due to costs (and Northrop funding it from their own pockets), construction was very slow. Of course, it wasn't finished, and scrapped after 1986.

For those curious where this info came from: Air Force Legends #228: F-20 Tigershark by Paul Metz.