Weird dash leak on my Lonestar

[Waterloo]

I had a leak like that, it was coming in in two spots that I can figure. Where the cab and the roof cap assemble, the gap above the windshield behind and above the visor. I loaded mine with silicon caulk. The other area was where the visor mounts attached to the cab exterior. Long story, but I had the dealer caulk around those four visor mounts with a body shop filler in a caulk tube, where they meet the cab, all four side. Since doing that, dry cab. Make sure you really fill that gap where the roof cap meets the cab, load it up. One tube is not going to work, I think I used around 4 or 5 tubes. Did it once, let it sit, come back in an hour or two and redo to get it sealed properly. I did all around the cab, right to the rear of the sleeper on both sides.