They sell aftermarket underbed spare tire carrier systems for the AD. At least Jim Carter was doing it for awhile, not sure if he still offers them. Going that route, you wouldn't have alot of fabrication to do. In truth, it wouldnt be that hard to design an underbed spare tire carrier. Rather than all of that sliding crap, you could just put a hinge on the back side. If that isnt your thing, a drawer slide. If I wasnt so busy already, I could draw something up.. so if I can do it, anyone can.