2SK3563
Toshiba ยท Field Effect Transistor Silicon N Channel MOS Type
Possible alternatives.
STP5NK50ZFP
N-CHANNEL500V-1.22Ohm-4.4ATO-220 / FP / DPAK / IPAK / I2PAK Zener-Protected SuperMESHTMPower MOSFET
STP4NK50ZFP
N-channel 500V - 2.4 Ohm - 3A TO-220 / TO-220FP / DPAK / IPAK Zener-protected Supermesh Power MOSFET
Both ST Microelectronics parts and may be more readily available.
