replacing lowrance x125 with humminbird

I'm replacing my THIRD Lowrance x125 with a humminbird. I have a hole cut in the dash that measures aproximately 5 3/4 by 4 1/2. I can't make the hole much bigger, so I need to know which humminbird to buy, that will fit. A 500 or 700 series. Did I mention that this is the 3RD one that has failed and I'm ready for a change.
thanks jc

look at the specs on humming bird web site that should help narrow it down. or you could always mount it on a ram mount to the side and get what you want. Maybe a 1197?:D:D

The current 500 Series or any 700 Series will fit the same cut-out

That might look funny, since there is a 997 right above this lowrance.