I got a Scotty 2 for my truck. I'm still trying to get all the right parts together, but I have a couple questions. First, there's a hat that goes on the end of the Uni filter. How is that thing supposed to stay on there? It doesn't fit snugly enough to just push on and have it stay there. It keeps falling off when I go to put the filter in the housing. Second, is there supposed to be a grommet that goes in the firewall to make a seal between it and the housing? I've heard good things about the Scotty, and I want to use it. I just want to make sure I get it installed right. Thanks for any help.