Centhot:
Here is where the other aircraft comes in. It was supposed to be a fighter, but became a trainer in the 1950's, then again a fighter, and split into two 'families' one was a radical change, whilst the other was an evolution, culminating in a design, which was lost in the 1980's partially due to politics.
This part sounds like the F-5 family
N-156 ---> F5A/B---> F-5E/F ----> F-20
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\--- T-38 (indirectly)
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\--- YF-17 ----> F/A18