Yes you can connect both units to the same GPS Receiver by using the AS-SysLink cable… but why would you want to do that? If each unit is using its own transducer you would want to mount the GPS Receiver as close to that transducer as you can so that the waypoints you mark will be that much more accurate. Plus you are going to be getting another GPS Receiver with that new 998c Si unit so it won’t cost you any more to mount the second GPS Receiver. Besides, the 998c Si will come with the GR50 GPS Receiver which is a little more accurate than the 997’s older GR16 GPS Receiver.