As far as I am aware Upper Saucon is on Lehigh County PD South. 158.835 PL 186.2 It is possible that they may still use 159.150 for unit to unit comms. According to the RR wiki, they would be 400 units.
It is my understanding that when Lehigh went to the full fledged 911 county system, all PD, FD, and EMS were brought into the county system for dispatch and the frequencies they used were also brought into the Lehigh County system. Many of the "old" frequencies are still used but now may be listed under the county and not the department.