Engines and transmission are from German companies. Not sure about the main gun, I think I heard that it is a licensed copy of Rheinmetall Rh-120 L/55. Armor is from POSCO (Korean), most likely electronics are also all Korean, idk about other stuff. So it is not a fully indigenous tank.Well I don't know for sure. The South Koreans off course are gonna claim it's fully indigenous. The butthurt Westerners might say that the 120mm L/55 gun is copied from the German Leopard 2A7. The 120mm cassette autoloader and armour is copied from the French Leclerc. The engine is copied from the Germans. The Thermal sight system is copied from the Israelis. The cupola machine gun is copied from the American M2. Well, anything that they can accuse China of copying from the West. They can easily do the same with the South Koreans.
The West lamented the sale of military technology to the Chinese. Giving the Chinese the technology to develop modern indigenous designs. But when the South Koreans bought Western technologies, they did the same thing. And now they are selling arms to NATO members. So double the butthurt.
SK defence products are very competitive in certain areas. Hence the question now is, how long would the US and the West tolerate this new competition in town?
EDIT: judging from Wiki, the newer batches come with Korean engines as well.