Very rare GENUINE NEW (Never Used) Sanken TO3 transistor 2SA909.
That transistor you can find at output stage of Sansui AU20000 or at G9000, or at G22000 and G33000.
Today you can find so many fake TO3 Sanken transistors, because Sanken doesn't produce that type of transistors more than 20 years. Fake transistor can make so much troubles on yours vintage audio, because in the most cases, fake transistors doesnt have specifications like genuine Sanken transistors. On the next picture you can see how it looks like a genuine Sanken 2SA909 transistors