If you have a factory rack base, Yakima racks has adapter plates and towers for it that hold round bars for racks. Thule probably has a similiar system with square bars. Yakima stuff is pretty easy to find on Craigslist. The only component that is specific to your truck are the adapter plates known as "Landing Pads". I think they are the same as the Ford "Exploder" ones.
If you don't have a factory rack base, the outfits mentioned above have rack towers that clamp between the body and the top of the door. These tend to cause rust in that area though. (Maybe not so bad if you're not putting salt water laden toys up there like me.)
You might do a Craiglist search and find someone selling a factory rack cheap. I gave mine away.