Everything you wanted to know about 3rd brake light gaskets....
The gasket is made from the highest quality material that can be purchased; EPDM foam rubber. EPDM is what all modern industrial building roofing and automotive weather-stripping is made from. Not Neoprene. That's a completely different animal. That material shrinks, dries out and is not UV stable.
1) I have a 2017 Ram 2500 with one of my gaskets on the light for the past 3 years. No leaks. I actually removed it a couple times just to verify. When a gasket leaks you can always see the dried up mud trail (from road dirt and dust) of where the water infiltration.
2) IF there is a leak ITS NOT THE GASKET. It could be; the light is warped, the roof is warped (had one guy actually text a picture of his truck. When I asked what happened to the roof he said his YOUNG KIDS JUMPED ON IT), the rear window seal is leaking, those stupid rubber strips that run down the sides of the roof seams are leaking, the cab lights are leaking, the satellite antenna is leaking. The 3rd brake light is JUST a gasket. It wont solve world peace or fix a flat tire. It doesn't fix any other issues except the 3rd brake light leak IF everything is mechanically sound. Its like if the engine is running rough and you install new injectors and then complain the injectors aren't working. May not BE the injectors. May be a vacuum leak. May be a bad O2 sensor. May need plugs.
I sell Honda taillight gaskets. Those guys are notorious about saying their taillights still leak. But on Hondas there are 3rd brake lights, sun roof, antennas that leak. And on some models they actually have like a dozen clips that hold the rear window trim on. The plastic clips fit in large 1/2" square holes and have cheap gaskets on each of the clips that dry out. What a STUPID design. On those models, THATS usually the problem not the taillight gaskets. But since the customer isn't AWARE of the gaskets on the trim clips it HAS to be the "defective" taillight gaskets they replaced.
3) You wouldn't BELIEVE how many guys will rip the gaskets in half and then say the material must be old or "defective" (love that) cause they forgot the kindergarten lessons about how to color in the lines, use scissors oh and how to remove an adhesive liner. I now actually have to include a video to show how to peel a liner off. Quick preview of whats gonna be on the video; you pinch the gasket on the sides below the liner and it POPS OFF. Maybe I should include instructions
4) IF the gasket doesn't fix the leak (again, its not the gasket then) seal it with clear silicone. It'll still be removable and then you can find the actual leak. In fact why not just install an LED bulb and use silicone and be done. Not sure why the factory didn't do that?
PS I GUARANTEE the factory did not improve the gasket material. All the manufacturers use the cheapest products they can. BMW SUV's use the cheapest neoprene (that I spoke about above). When they dry up after a few years it destroys a $1000 taillight. Hondas use the same crap material.
PPS In the gasket world thicker isn't better. Else why not use use a 1/2" thick gasket? All thicker does is distort the light. The light isn't made from tool steel. You tighten the 2 screws on the ends and guess what the middle does. That's why most plastic parts have those stand offs/limiters built into the screw bosses so you cant overtighten. But the standoffs are designed for a specific thickness gasket. Not a thicker one.
Guys have been asking for gaskets for the new $1000 3rd brake light with backup camera built in. Factory doesn't sell a replacement gasket (why would there be a need for a replacement gasket if it's "improved", right?). You have to buy a whole new assembly. Nice.
