From researching this a year or so ago, I don't think that Ford ever made one for the Expy (although there appears to be provisions for one in my father's 2010 Explorer.
Although it doesn't retract, I ended up making my own for my 2006. I had some 1.9 oz Multicam ripstop nylon at the house that I cut and had sewed with full length pockets on opposing sides. For the front I am using a spring-loaded shower curtain rod. At the back I mounted a pair of plastic closet rod mounting brackets (
http://www.homedepot.com/p/ClosetMaid-3-in-Closet-Rod-Side-Wall-Bracket-2-Pack-1058/100144901) painted tan to match the interior, and then attached just inside the hatch with 3M double sided mounting tape. I then used a piece of 3/4" PVC and a pair of 3/4" to 1/2" couplers as end pieces to span the gap just in front of the hatch. It may not be the prettiest of cargo shades/covers, but it does the trick.
The attached photo roughly shows what it looks like, even though I was only using a pair of spring-loaded curtain rods at the time. The revised version described above works out much better.
I hope that this helps. It was the best i could come up with.