and the unit mount (gimbal).
Depending on when the 997c Si unit was made you may want to swap out the power cable and the GPS Receiver.
The power cable has been changed to one that has a built-in noise filter (choke) in it.
The 997 may be using the older GR16 GPS Receiver. The 1198c Si should have come with either the GR50 or GRP GPS Receiver which will work a bit better than the GR16 will.