30"? First step? The lowest systems would be the house batteries/Electrical supply and the leveler's hydraulic pump. Any of those that went underwater will need to be replaced. Your drivetrain should be good to go unless the rear differential vent went under, then it would need to be drained/flushed and refilled. Other than those items you should be good to go: what kills flooded vehicles is drowning electrical systems in the engine and dashboard, then they are total losses.
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