Humminbird Interlink with cables. $100
I had this connecting a 798 and a 998. I upgraded to an 1199 and need to buy a new Ethernet box.
"The Interlink will not work with any of Humminbird's 2014 products in the 11X9ci, 9X9ci or 8X9ci Series of products. "http://www.humminbird.com/Products/AS-INTERLINK/
Unit was just taken off the boat and worked fine on Texoma yesterday.