The socket on the radio end is Kenwood P/N E56-0410-15
The plug on the microphone isn't available on it's own from Kenwood, but you can buy the replacement cord for the KMC-27/KMC-28 microphone, has an RJ45 plug on the end to plug into the bottom of the mic and the 12 pin on the other to plug into the radio. Kenwood P/N is E30-7647-05 List price is about $49.
Might be better to just purchase an old microphone off e-Bay and "roll your own".
The connector itself is listed in the service manual as "Universal 12 pin connector".
Only source for these I've been able to locate is direct from Kenwood.
1 SB O Power output after power switch (MIC (13.6V or 13.4V±15%)
2 HK I Hook signal input. “L” : On hook, “H” : Off hook
3 ME – MIC eearth.
4 MIC I MIC signal input.
5 E – Earth.
6 TRD I/O TX data output/RX data input.
7 NC – Not used.
8 DM I/O Serial data input/output for keypad MIC.
9 BLC O MIC backlight control signal output. “H” : On, “L” : Off
10 PTT I PTT signal input.“L” : TX, “OPEN” : RX
11 NC – Not used.
12 NC – Not used