Does the 65 series fill the tray? It’s too freaking cold to go look what I am running. Off site storage, 7 deg F, and bronchitis from hell (not Covid) make that a bad idea.
I probably have a group 58, AC Delco from Menards, 3 or 2 years outright, lead acid, not AGM.
This chart will be helpful on a bigger screen
The stock size battery for my LX 5.0 is not as long as the box, front to rear of the car. I have two PVC house trim pieces cut to take up the space and prevent sliding should the clamp start to loosen. I should look up the class with the right length to fill the box, and with the same width for the stock tray.
If one has a bigger CCA and reserve capacity, some extra weight will be worth it. But bigger batteries are not always more powerful.