Tail Gate Rattle

I recently bought my 07 Tundra off a private seller. I’ve noticed the tailgate has a nice rattle to it and it doesn’t seem to fully sit. It locks and closes but I’m able to wiggle it back and forth. Anyone have an idea on how to fix this??

 

Not exactly the same situation, but my 08 would seem like it closed, but wasn't quite all the way closed. I don't remember if it rattled. Slamming it would get it to close all the way, but then it was hard to open (the tailgate handle was hard to pull). I put some synthetic grease on what I am going to call the D rings (the two D shaped metal pieces on both sides that the tailgate latches onto) and worked it in. Shuts easy now and is easy to open. If grease doesn't help, you may want to watch the gap between the tailgate and truck to make sure nothing is binding.