Manchester Township moved to a P25 trunked system around the same time Montclair went to their Type II trunked system. I haven't heard them use 158.7900 MHz since they switched.
BTW, Montclair has a license for a repeater on 158.7950 MHz on the same license as 158.7900 MHz. 158.7950 MHz isn't a valid frequency, though.
EDIT: They also have a licensed repeater on 158.6800 MHz, but that's not a valid frequency.