on the head right above one of the exhaust ports is a stamp with the head code. if it says pr3-xxx it is more than likely a jdm type r engine. if it says p73-xxx it's most likely a jdm gsr engine.

fyi, jdm engines dont have a number after the letter designators ie. b18c1, b18c5, etc. only usdm engines will be stamped that way.