Welcome to the board from Greenbrier. They are like Fords and Chevy's. If I was going to buy one that size, with si/di, single I would really look at HB 1198. If running 2 I like the Lowrance with the LSS1. Sounds like you may have a LCS lowrance if you have external antenna. If it has the blue connecter cable, it will hook to new HDS, but will not share w/p. Spending that much money,I would have to go see both of them in action. They are both excellent.