Bull bars are similar, will come up about half as high as a grille guard, are more curved, and don't cover the headlights. Google image search them.
Finding a solid (or VERY heavily gauged) steel or metal grill guard will (in my opinion) be damned near impossible, due to manufacturing methods and extreme price.
My knowledge on that last part may be more limited than others. Perhaps someone knows more about heavy-duty guards made for explorers.
Hunter (Truck Gear Direct) makes black and chromed grille guards at affordable prices with the headlight pieces removable. I currently have just the center of the grill guard on without the headlight pieces (have to fab up a quick bracket to raise the whole thing 3" first).
From what I know, nowadays grille guards are really just for looks, mounting surfaces, and helping to absorb some of the blow in a mild hit. Anything stronger can actually be detrimental, transferring too much impact force through the frame and chassis. I've heard a few horror stories about hitting a deer (and such) and having the grille guard stay solid, but the underside of the truck bent slightly. Just my thoughts.
-Dubya
