Welcome to the Unofficial Humminbird Side Imaging Forums smithskier70.
Yes and no. The Piranha 1 used a 24 degree 200kHz transducer while the Piranha 20 uses as 200/83kHz (20/60 degree) transducer. The Piranha 20 could work on the Piranha 1’s transducer but could only do so using the 200kHz (not the 83kHz). For full functionality you would need to use the correct transducer with the Piranha 20 unit.