Be sure when deciding to upgrade to the Gtn 750 to consider all the functions available with this new box. It can control alot of your external devices right through the 750. Audio panel (probably with marker beacon function still) and transponder can be remote, plus a wide array of support devices are available. ADS=B, music weather traffic, all controlled through the front of the 750.( Right , there even a remote box for texting right through the 750! It's ok to text and fly?)