If your gasket has a groove in the outside its for the stainless trim. If you don't have the trim it will be almost impossible to seal the windshields with this gasket. Also, if you do need to shim, use a plastic windshield stick to work the shim in. A handy tool for rubber gasket installs is a cotter pin puller, aka radiator hose tool. This is used to help get the gasket started over the pinchweld, especially on the newer trucks that have a double lip on the gasket. Round the point on it first. A new one will easily puncture/ tear the rubber. John
