Already, prep for a decently long thread:
So, the first constructed Tigershark was originally known as “F-5G” (but was later re-designated to F-20 when the change was approved). It was the closest of the 4 variants to the F-5E, retaining the same nose (specifically shark nose of the later-build F-5Es) and cockpit section. It differed by way of Leading Edge root extensions (increased in size, shape changed to a “chisel”), engine, rear fuselage, and intakes. However, it lacked the APG-67 Radar, updated cockpit, and so on. While it did get the new engine, it was unfortunately the least powerful version of the F404, the F404 (only 16,000 lbf in reheat/afterburner). It still had the same weapons capability as the F-5E, but was also more suited as an actual testbed/test aircraft, rather than production airframe. We’re likely not going to see this one, unless Gaijin is that desperate for money lol.
Illustration of early Tigershark cockpit here:
Spoiler
Next up, we have Tigersharks 2 and 3:
2 and 3 began adding a lot more proper production changes, the main ones being the updated cockpit with HUD (smaller version), re-designed cockpit with radar warning and two monochrome multifunction displays, the more powerful base F404-100 (17,000 lbf), the APG-67 radar in a slightly re-designed nose, and the larger panoramic canopy replacing the F-5E canopy of old. These are probably the most likely to be added.
In terms of weaponry, you’d be looking at 6x Sidewinders, 2x Sparrows, 4x AGM-65Bs, dumb bombs/rockets, and the same RWR and CM dispensers as the F-5E.
Three different cockpit configurations, first being for testing, second being production, third also being for testing:
Spoiler
Finally, there’s the main one that I (and a fair few other folks) am hoping for, especially now that more info has been revealed on it: the 4th prototype.
The 4th prototype was under construction, and was even a little less than halfway built by the time of cancellation (the nose section popped up for sale on ebay a few years back, disappeared, and has possibly been lost to time now). The main changes here are the introduction of electromagnetic servos for the control surfaces, making it a fully digital aircraft. The wing area was increased from 186 square feet to 200, decreasing wing loading and allowing for slightly better turn rate. The nose was slightly re-designed, with the radar being repackaged to allow for an extended range. With the new cooling system and CWI for the Sparrows, gun ammo was reduced from 500 to 400. The engine was further uprated to 18,000 lbf in afterburner/reheat, and the original HUD was replaced by a wide-angle HUD. This was the Tigershark that was pretty much competing against the F-16 for the Air Defense Fighter contract in the mid-80s, for the US Air National Guard, so it likely would also have access to the AIM-120 AMRAAM (this was planned since the early 1980s).
Images of the improvements, cockpit, and such:
Spoiler
Bonus image set for how the MFDs and HUD look, symbology-wise:
Spoiler
Extra stuff:
There were also proposals for a CAS-focused F-20, which was meant to compete against the A-16C or F/A-16C, as well as proposals for even further modified designs (originally known as F-5H and F-5J, but renamed to F-20C and F-20E) and even two-seat models. I can post those if anyone’s interested.