http://www.answers.com/topic/f-5-freedom-fighter
Various F-5 versions remain in service with many nations. The
most advanced are those of Singapore, which has approximately 49
modernised and re-designated F-5S (single-seaters) and F-5T
(two-seaters) aircraft. Upgrades include new radar, manufactured by
Israel, updated cockpits with multi-function displays, and
compatibility with the Rafael Python and AIM-120 AMRAAM air-to-air
missiles. Similar programs have been carried out in Chile (with
Israeli assistance) and Brazil, the former being called the F-5E
Tiger III, armed with Python III and 4 (with Dash helmet-mounted
cue system) and new radar, cockpit displays, and electronics, and
the latter being called the F-5 Plus, with Griffon radars and other
improvements. It is believed that the Chilean Air Force F-5E also
carry the Israeli Derby medium range missile, proving the aircraft
with BVR capability.
Well, at least we are recognised to have the most advanced F-5s
by answers.com 
