Trev, the DSE crossmember is tucked up into floor similar to their subframe connectors, and runs from one rocker panel to the other in length. The only portion of it that hangs below the subframe is the actual transmission mount. They built it in this fashion to allow for better exhaust clearance as well as to stiffen the chassis itself.
The other crossmembers you see advertised span from one rail of the subframe to the other.
You can see DSE's
here.