It is possible to install a front bumper on the rear, might have to flex or massage the bumper or brackets.. or use panel truck brackets which used a front bumper. Those who have have seen 1/4" rear bumper might have seen one of these situations.
Otherwise you could use 3/4 ton brackets and 1/2 or 3/4 ton rear bumper (straighter than the front).
1 ton rear bumper might not have been factory, but also not impossible or unheard of.
