The difference is, that Rover cost a couple BILLION dollars. They spent 29 cents on your tank indicators.
I fill mine until it spews out the overflow. My fresh water tank is in the far rear, and the garden hose fill is in the front. But the overflow (vent) is on the side of the trailer near the rear. When water spews out, it's full.
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History is not about the past, it's an explanation of the present.
2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually