2SD1426 silicon NPN transistor with damper diode by Toshiba. Package: TO3-P(H)(BS) package - ugly looking thing Download Toshiba 2SD1426 datasheet: Status: NOS (New Old Stock) (Note: these always test as 2 x common cathode diode if tested on Peak DCA74, this is nornmal) (resistance between Emitter & Base will be about 50 Ohms. ) RoHS compliant: no