T-38C Talon NASA Space Shuttle

Beginning in the 1990s NASA's T-38 fleet was upgraded significantly. A glass cockpit and color weather radar were the first phase, resulting in a very different profile. The metal nose gave way to a radome. The small size of the T-38 nose mandated bulges above and below to accommodate the radar scanner. The intakes and exhausts remain as before.
By the mid-2000s, the full upgrade again significantly modified the external appearance of these veteran steeds in parallel with the USAF T-38C program. They are either officially or unofficially called T38-Ns. The full modification includes completely new and much larger intakes (unlike those fitted toi any other F-5 family), new exhaust nozzles, a shark fin comm antenna, and Martin Baker Mk.16 ejection seats along with other improvements.