cc4bama,
This is only partially correct:
The IDMK-700 should not be used on some of the older model 700 series internal GPS Receivers due to where the internal GPS Receivers were located (I am trying to get a listing of these) and I think that this is where this statement that is on the Humminbird web site came from (I did not see it in the 2011 catalog).
A few years ago we switched where the actual internal GPS Receiver are located within the units (it is now above the keypad) so they can function properly when indash mounted and so can use the IDMK-700.
However, the 798ci HD Si unit cannot use the IDMK-700 – not because the mounting bracket itself will not fit but because the connector collector will not work with the new connector configuration that the 798ci HD Si uses. So a new indash kit is being developed that will work correctly with the 798ci HD Si and will be called the IDMK-700E (E for Ethernet) and this is what you will need.
Confused?