—The Unha-3/TD-2 upper stage: The third stage of the North Korean rocket was developed in Iran and uses liquid propellants.
This part is interesting to me and is consistent with what I have read about second stage of Safir in Persian language sources.
Around two years ago an exhibition was held in Sharif university. One of the visitors of that exhibition wrote a good report about that exhibition and posted the photos of it too.
According to his report engine of first stage of Safir SLV has been engine of a ballistic missile (we know it too) that Iran has reverse engineered it and has built different generations of it.
But he says unlike the engine of first stage ,
engine of second stage has been built by a engineering (designing) work not a reverse engineering work. He says " This engine is built in "Space Research Institute". Before Iranians, scientists of South Korea (I don't know does he really mean South Korea or not he has meant North Korea?) had tried to build this engine 7 times but each time after just 3 seconds the engine is exploded. Iranian young scientists try to build this engine 5 times and the engine works (burning time of engine) 150, 320 and 350 seconds in the last three times and finally the engine of second stage reaches to operational stage."
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He says in Simorgh, this engines of second stage will be replaced with more thrust engines (I think these more thrust engines are the same bigger nozzle engines that has been talked about them in some artciles):
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http://forum.avastarco.com/forum/showthread.php?220-%D9%86%D9%85%D8%A7%D9%8A%D8%B4%DA%AF%D8%A7%D9%87-%D8%AF%D8%B3%D8%AA%D8%A7%D9%88%D8%B1%D8%AF%D9%87%D8%A7%D9%8A-%D8%B5%D9%86%D8%B9%D8%AA-%D8%AF%D9%81%D8%A7%D8%B9%D9%8A-%D9%83%D8%B4%D9%88%D8%B1&s=f76d3c5d71029a1ddbd99ee6b45c1770Although it is said engines of second stage of Safir is based vernier engines of Russian R-27 missile, but difference of thrust of that engine and engines of Safir is very much so that it is possible to say engines of second stage of Safir isn't reverse engineering version of vernier engine of R-27, Thrust of vernier engine of R-27 is around 15 tons but thrust of each engine of second stage of Safir is around 3.5 tons.