It could be either one Robert. The only way to know for sure would be to physically separate them and see if it anything changes.
Ddono,
Chuck is right though: “It should not cause any gps issues unless the signal reception area is physically blocked” but we know it the real world that things do happen that are not always planned for. I would temporarily mount the 998 unit and GPS Receiver to check it. Be sure to run the cables as close to where they will actually be located as you can as this can influence the possibility of interference.