I'd measure it up ,test-try it,then use the best contact-glue you can lay your hands on. REALLY clean the surface on the tailgate And also clean the seal -Use silicone-remover. Then put on a nice even -Not necessarily thick but Nice even layers on Both mating surfaces.
You already have the tailgate removed so be sure to glue indoors as correct temp is vital to get good result!
The MOST Important thing is to let the contact-glue dry for the correct period Before you try putting the seal in place-If it says on the it to let dry for 1hour-Do NOT be tempted to mate the seal premature!!!!
Remember- contact-glue Bites and sits at ONCE! so be careful to start where you planned to when testing it. Apply in an evenly nice way- Do NOT stretch it as this will come back to bite you if you do.
It's good to have an "assistent" to help hold the seal off of the tailgate until you place it Just where you want it.
Good idea to put some weight on it overnight-or use tape to hold it in place. Be careful so tape or weight don't get it to shift position....
Any glue-stains? leave for 24hrs then Roll it off using your fingers...-R.
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