Batboard

I recently purchased a Motorola RKR1225 in outstanding shape and acquired a CSI TP-154 controller. The wiring for the RKR1225 were already setup for a Zentron controller however, I have a TP-154. All the connections are complete except for the RX COS. I'm having problems distinguishing which pin number it is on the rig in order to connect it to the TP-154. The service manual dosen't really indicate what pin is the COS. Any assistance would be appreciated.
Mark KM7N