The Phalcon is an Israeli radar system that can be fitted to several different aircraft, includung the 707 and C-130. The KJ-2000 was a copy of the A50 fielded with a different radar system after the Russians cancelled the deal to sell the Chinese the A50 due to US pressure and has other detail differences.
I'm guessing there gun ports - thought it was the top two .50 cals on a Sabre at first, but they're the wrong position. I'm thinking 20 mm cannon, but can't put mu finger on it - unless it's a late-production Sabre?