Can I replace 2SK170BL to 2SK43 in BOZ and B1? The supplier at my town offer this 2SK43 with cheap price. After I checked the Idss, the value is about 7.x mA. The price is 20sen each. The specs I found is from 0.9mA till 14.3 mA max.
2SK43 was obsolete in 1985 having been made by Sony in 1979.
Not as good as the 2SK170, made in 2005, a lot noisier.
It will probably work but I don't know for sure as you do not say what employment you have in mind.