OK good buddy! I've been trying to figure this out. I've been scanning through YouTube videos and looking at photos of your model on-line. And here's something I found.
Here's a YouTube of your year and model. Jump to about 20:15 into the video, and hit pause at 20:26 on your computer to "pause". If you notice, this is showing a clear picture of the driver's side rear corner of the camper. There is your 50 amp plug and slightly above the plug and forward of the plug about a foot (may 18 inches) is the half-moon shaped vent. This is the same location as mine. Your tank is in the rear? Correct?
If that vent is not there, then I think something is wrong. Your next step should be to try filling and see where water comes out when full, and then contact your dealer if water comes out the underbelly.
YouTube Video, got to 20:26 and pause.
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2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually
