The KSC-76 is the 6 bay rapid charger for the KNB-5,6, and 7 batteries. It may also do the batteries on the Tk-250/350 (KNB-11?) correctly. I have used it on the KNB-5,6,7 with great success.
It will not do the batteries in which you are interested.
I am fairly sure, but might be wrong, that KW moved to non-selfcontained gang chargers with the newer radios. By that, I mean if you want 6 charging slots, you must buy 6 chargers and an adaptor to hold them together as one unit.
Here is the data I have.
KNB-14/15 batteries use the following chargers:
KSC-15 Regular Rate
KSC-16 Rapid Rate
KSC-21 Rapid Rate with battery discharge
KSC-23 Regular Rate
KSC-24 Rapid Rate
If you get a KMB-14 you can adapt 6 KSC-14 or KSC-15 charges to be one "unit".
As for the KSC-76, not only does it do the KNB-5,6,7 batteries. It also does KNB-9, 11, and 12