Well, took the boat to the dealer and the 899 came out pretty easy, now that Ive seen someone else do it. Hooked the 899 to the front unit that has an external antenna and it worked fine. Put it back on the dash and GPS would not work. Called HB and they made us turn it on for 30 minutes after resetting defaults to see if it would work. Long story short, the 899 is on its way to Alabama.