Goodcooker covered it, but to clarify-
4.7K mod is an option for adapting 3-wire low-voltage, non-balanced, non-phantom powered microphones to 2-wire mode for high SPL use. Most of such mics will be miniature ones (AT, Countryman, etc). The mod is not required for 2-wire mode, but is recommended for recording loud source material to help avoid overload. It is not recommended if always recording quiet material as it will reduce sensitivity and raise the self-noise floor somewhat. The mod is often installed so as to fit within in the microphone connector housing. Alternatively it can be installed in a separate adapter cable, which allows for use of the mics either with or without the mod. Likewise it is sometimes installed in the battery box or preamp - and sometimes made switchable, sometimes not.
Termination connector used for the microphones is a separate issue. A pair of 2-wire 4.7k mod'ed mics wired as a stereo pair to a single connector requires 3 channels through the connector (Left signal & power, Right signal & power, shared ground) and may be terminated to any connector with 3-or more contacts. Most common for tapers is termination to a TRS stereo mini plug or a 3-pin TA3 mini-XLR.