use Automotive Goop! That stuff can hold anything to anything. I used that stuff to hold on te 5.0 emblems and they have been together for 4 years now...I also glued a Don Quixote statue back together with it. :OT: But you can get it at auto zone/advance for like 3-4 bucks!
The correct way to install or replace your tail light lens is to use butyl. you can either buy a tail light installation kit from 5.0 resto wich iuncludes the butyl and clips or you can go to your local auto parts store and get a strip of butyl usually as a windshield installation kit. you will need about 3 feet of butyl for each lens and 6 clips . I believe the diameter of the butyl is 3/8 or maybe a tad smaller.
hope that helps
Travis