37, I do watch the forum, and as far as the tailgate assist, a search on gas hinge doesn't bring back any valuable results. Please grant new members a benefit-of-doubt that they didn't use search terms that are common to others who have been here longer.
With that said....
Folkstitan, Welcome to the forum, and there is a current discussion going on regarding installation of the '5 tailgate assist mechanism onto the '4 titans, and that thread is located in one of the vendor forums... here....
Easygate tailgate assist
Although this thread has degraded over time with posts by a user (tom) experiencing issues specific with his truck, there is valuable information in there.. in that it looks like the stock '5 bed may be made differently to support the new mechanism for the tailgate assist. But no one has really stepped up yet to confirm nor deny that info.