Does anyone know if I can replace the Autohelm Depth/Speed display with one of the newer Raymarine st40 or st60 displays? Mine has a crack and the numbers are barely visible. The transducer is fine, so I'd like to just replace the display. All I need is the depth as I can get the speed from my GPS. If anyone has done this, I'd sure like to find out what is involved. BTW, my boat is a '94 23.5. Thanks!