2N6059 SILICON NPN POWER DARLINGTON TRANSISTOR. TO-3 Package. The 2N6059 is a silicon Epitaxial-Base NPN transistor in monolithic Darlington configuration mounted in Jedec TO-3 metal case. It is intended for use in power linear and low frequency switching applications. This 2N6059 is higher rated and can be used to replace the 2N6057, 2N6055 and SDM4004 transistors. This is very common in Williams power supplies and many other applications.