Alan Bowers

My cab is leaking and has been intermittently for years but I cannot make it leak in order to find it. It could possibly be the third brake light, which I have recently re-gasketed, my vents behind the rear seats, or my clearance lights. For this post, let's just go with the clearance lights because i actually think I have them leaking as well as one of the problems in the back (2 different leaks). I ordered new lights and installed them today. However, the gasket on them is much larger as well as thicker, and the screws are slightly longer but also slightly smaller in diameter. I tried to use the old screws but they wouldn't pass through the little gaskets supplied for the screws, plus they probably would have been too short with the thicker gasket. Here's my problem and I will try to post pictures or a link to them. When tightening, the screws never felt bottomed out except on 2 of the lights. I never could NOT turn the screw, yet when turning, I couldn't see the gasket compressing further. They didn't feel like a typical stripped insertion either though. They do not fit flush against the roof like the older ones did, so I am concerned they will still leak, particularly because of the tightening issue. Anybody know if I'm going to have a problem due to the gaskets possibly not compressing enough?
In the first picture, you can see where the old ones fit flush and the new ones in the distance don't. In the second, you see the difference in gasket thickness (and size), along with a new and old screw for size comparison.