Skaha the fishin buddy line is owned by Humminbird now and goes by numbers for the different models. the old I & II arent made anymore and are almost impossible to get replacement parts for as well
I own a Fishin Buddy 110 and my dad uses a 120. only difference between them is he has a side view option but he doesnt use it because it drains battery life quickly. the 110 is perfect because it gives you water temps and depths of the bottom, structure and even fish swimming by to give you an idea where they are.
Dan-O : i have the exact same pontoon as you do and just have the fish finer mounted with the strap mount. I will make one suggestion though to get the one made by Cabelas because the strap is alot longer than the one made by Humminbird. i have the "proper" one and it fits very very tight around the pontoon(loose as possible) where my dads (cabelas) has extra strap he can adjust still