Okay so when I bought my car the plastic piece that is in the trunk was removed. I know I'm missing a few fastners but even if I had them it doesn't look like the piece would still stay in place. There are two fastners on the top by the latch and then there are two more fasteners on the left and right bottom. I have all those in place but how does the top left and the top right stay in place? I don't see any fastner holes or anything like that. so the bottom part is fine but the top part has a huge gap in it. If that's too confusing I will upload a picture in a minute.

 

There are 2 large fasteners on each side half way down that are the main tie downs. along with the small ones they set in an indent can you locate them and are they in place? if so try pushing them in more if not that is what is missing

 

ya the fasteners at the top just push in tere should be a hole in the plasticwhere they go

 

I too am missing one of those large fasteners. They go thru the liner and attach to the top threaded post of the taillight. ** if you go to Ford to buy a fastner, DO NOT buy part W712314 S300 nut wing. That is not the right part. It shows that part on the diagram, but it is a hollow sleeve and although it doeas fit the hole, it doesn't grab onto the threaded post, rendering it useless. I even took the one from the other side down to Ford and they didn't know what it was!
So if you happen to find the right thing, let me know!

 

i certainly will i havent had that problem i lost one of those little ones by the latch when i was putting my tail lights in

 

You can get those little ones (push pin looking with its own clip) at NAPA, they have all different plastic clips & retainers.Kind of handy to have a bag of them around, the same ones next to the latch are used in the engine compartment too on the radiator cover. But that one that grabs the taillight thread is a pain in theA** to find.

 

thats a good lookin ima have to go get some of them

 

Okay I see what you guys are talking about but I guess the person before me broke them off. Instead of snapping in the plastic snap pieces are broken and serve no purpose anymore. I have a junkyard close to there with a few 05+ mustangs so I might go up there and check to see if their's are intact