This is a Panasonic 2SC539 from the 1960s-1970s, the same as the real one that is famous for the UNI-VIBE. Needless to say, it is very hard to get hold of. In recent years, I have come across 2SC539 transistors online that are unmistakably counterfeit. I strongly urge you to use genuine parts to reproduce the true sound. I think I am probably the only person in the world who sells 2SC539s from this period. If you are purchasing from outside Japan, please purchase through the following agent.