I hear good things about Optima batteries, but they use a gel instead of a liquid inside. Best uses are for off road or boat applications, as the gel doesn't slosh around. You can mount those batteries at any angle.
I have an Interstate unit in the SD, came with it five years ago, still cranking fine.
I bought a battery from Advance Auto, the Titanium ~$12.00.

You need a group 49 battery, don't use a deep cycle battery, those are not designed to be continually charged, but drawn down to near "empty" and recharged fully.

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83 SD

84 CD