I started this thread several years ago. It seems Keystone hasn't done a thing to cure the issue of outside air being able to come in through the step grills. If anyone honestly thinks his pass tru storage or belly pan is totally sealed ... I have some ocean front land here in Wichita, KS I would part with. Like said ... over the years many have simply blocked the grills off for summer use, then unblocked for propane furnace use in winter.
https://www.montanaowners.com/forums...ht=design+flaw