I use two Duracell Group 27 AGM batteries from Sam's in my rig.
Group 27 dimensions: 12.0625 x 6.8125 x 8.875 inches (306 x 173 x 225 mm)...close to what you need.
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MikenDebbie Aggie ‘77 in the sticks near Austin TX
2019 Chevy 3500 High Country DRW
2018 Montana 3921FB
Aussie Gus + Texas Heeler Jimmy
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