If you have to flip the winterize switch, it is fairly obvious that whichever one you are hooked up to at the time is the winterize. The connections are labeled atop each one, three connections, three labels. Here is a photo that shows the convenience center of a 2011 Montana 3750FL:
They are difficult to read but the top is labeled Freeze Gard, the middle is labeled City Water which leaves the bottom for the black tank flush.
Bingo
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Bingo and Cathy - Our adventures begin in the hills of WV. We are
blessed by our 2014 3850FL Big Sky (previous 2011 3750FL and 2007 3400RL) that we pull with a 2007 Chevy Silverado Classic DRW CC dually.