T28B, the "original" plan (back in the 90s) was to purchase first the A-4ARs (A4-Ms with upgraded avionics) and later the F-16s. I fact, the ARG-1 radar was a downgraded APG-66 radar (with a smaller radar dish), the same the F-16 then had.
Of course, the plan was not followed. In fact, an AAF CO once said the F-16 is problematic because the intake could absorb stones in the Patagonian Airfields (yes...) and last year the Ministry of Defense argued against the F-16 because the Chileans have problems with the plane (what problems???)
I think the AAF wants two sources of planes. One american (A-4AR) and the other from elsewhere. Just to escape any "embargo" in the future.
Regards!