I want to get a second battery for my Supra. I will be installing new tower speakers and an amp and want to run dual batteries. Just wondering if anyone can tell me off the top of their head (my boat is not by me at the moment and I have off tomorrow)? I can easily just go to the boat tomorrow and look but it will save me some travel time since it is in the opposite direction of where I need to travel.

Any ideas? (it's got a green lid with a gray(?) body). I want to say it's an Interstate.