Here is a pic of my problem. I just purchased a "new" 1997 hydrasports bass boat. There is a recessed portion in the dash for this nonfunctioning lowrance to fit just perfect. I assume it came this way from the manufacturer. I would like to replace this with something that actually works. The dimensions of the hole is exactly 5" x 5". As you can probably see I can't make the hole any larger.

Any ideas?