Lawrence Elite 5 ??? On transducer????

Unit I bought used had a bad wire(Wire cut and patched). I'll be buying a new transducer through Defender.com or where ever I get the best deal. Any recommendation as to which transducer or am I limited to the original? What will work best? I primarily will be using it for depth and GPS in the coastal marshes. I haven't owned a depth finder since I sold my bass boat about 18 years ago. LOL..Yes, they've changed.
Tight lines
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