Side question - what (if any) differences are there between an F-5 and a T-38?
ISTR that the wing construction on the T38 was different in that it used a honeycomb internal structure, but I cannot find any confirmation that the F5 doesn't have this.
Re the F20, I was in SOAF when Erik the Boss came back from the demo of the F20, with its unusual (for the time) laser gyro systems being seen as the USP. He wasn't impressed, knowing that the far more capable F16 would be available before too long.