While changing my third brake light on my 03 F150 I found a crack in the trim on the right side of my cargo/third brake light. The crack extended from the weather stripping all the way through to where the cargo light is at. I read another post in the archives with the same problem. The crack disappears while in the heat of direct sunlight, but as soon as the sun either is shaded by a cloud or the truck is put in the shade the crack re-appears. The crack appears to be about 1/16" wide when it is cool. I tried JB Weld and it failed when the sun went down. Does anyone else have any other suggestions besides totally replacing the trim? I've considered getting some epoxy for plastics or trying some silcone that will at least fill the crack up. I'm open for suggestions. Thanks in advance.

Austin