Don't know if you have to, but you should. Mounting a new transducer doesn't have to be hard. Use the existing holes to mount a wafer board (might have to drill a couple additional holes too), then mount the transducer on the board. If you ever have to do again, it's easy. I've got a wafer board on both sides of the motor; with the side scan, I had to do some adjusting to get it just right and the board made it easy.
Looks like this for my high-speed transducer: