1. Here is a link for an image of what your 3D transducer should look like.https://www.gps4us.com/Lowrance-Xdcr-Str...CFYkjgQodQtoFKg
It has to be mounted somewhere outside of the boat.
2. The 2D transducer can be epoxied inside the boat in the bilge area. If you have two (2) inside they have put in an extra transducer for you. Perhaps an 83/200 and 83/200 HDI?
3. Here's how I set up my Ranger:
a. 1-Transducer outside for down/side/3d.
b. 1-2d Transducer outside (50/200) This transducer is much stronger in construction and can take much more abuse than the standard 83/200 and is generally used for salt water apps, however the 200 works in shallow fresh water applications too. (Use the 200 setting for shallow water)
c.2-2d 83/200 transducers epoxied inside. I normally use one of these for 2d images and always have one for a spare just in case and the 50/200 outside is also used as a spare or when I really need best possible 2D images with no loss with one of the shoot thru hull units.
d. Keep in mind you will have to always adjust and select the type transducer you are using to show the best images on your Gen3.
e. If in doubt, I would ask the dealer to show you exactly where and how many transducers were actually installed on your new boat.
f. When in doubt call Lowrance. They have excellent technicians.