On my 2007, I also get a lot of dust infiltration. I found that the vast majority of it is actually coming from the gap between the tailgate and the bed floor. Dust gets kicked up by the wheels and underbody drafts, and gets flung through that gap at pretty high speed. It will often go high enough to coat the inside of the rear window. A bed gap guard or something else that covers that gap (like a BedRug) might eliminate a lot of that dust infiltration.

 

Sounds like some simply foam or 3M door weather stripping would solve that problem. But would it last the test of time?

 

It's a much larger gap than you might think. Probably 1.5-2" wide, and as long as the tailgate. Definitely large enough to lose important things out of. (Or to have some very large rat crawl in at 2am to visit you...)

Eventually I just took to plugging the gap with whatever I had on hand. Keeps things from falling out and slows down mice and mosquitoes from getting in.

 

I remember a time when my dad looked at pickups tailgates from the perspective of "you don't want the grain falling out of the crack as you haul it to town". lol

 

For those with a dust issue, this might help.

https://accessories.ford.com/product...ed-dust-seal-1

 

I just got my Bedrug yesterday will be installing as soon as it warms up a bit. As for caps, my last truck had a fiberglass cap and I am shopping for a new one, so many choices out there, makes it hard to decide.

 

I used a bunch of foam weather stripping and custom cut it to fill all the gaps as best as possible. It worked well, but some of it is now coming off 8 months later. Just ordered the Ford kit that @Member No. 1 posted, and will update with how it works out.

I have a Snugtop topper, drive on dirt roads a lot, keep bikes and snowboards in the bed- stuff I don't want covered in dust, and even sleep in it some throughout the summer, and the tailgate gap that lets dust in drives me nuts. I've gone so far as to tape over all the mounting holes in the bed and apply silicone weather sealant around all the gaps between wheel wells/bed floor/bed sidewalls.