STBYRUD

That has nothing to do with new versus old aircraft, all depends on what the initial customer ordered. What I know is that the Telex ANRs work fine powered through the twin plug arrangement on the mic bias.
Anyhow, you are talking about the CAP - that means there is no battery box and the thing needs pin 5 to be wired and hot for NoiseGard. The KAP on the other hand would use the mic bias and a common ground for power (which should work on most twin plug AC), the CAP will remain without active NC if you connect it to anything other than a fully wired XLR-5.