The rear bumper impact bar REINFORCEMENT BRACKET and rear bumper impact bar ARM (what you appear to be calling a brace) are two separate pieces that attach together, bolting to the frame on one end and to the horizontal impact bar (crosspiece)
These two pieces sell new for about $100 each. This ebay seller has both 'Used' (look practically new) at a steal of a price ($90)including the shipping. I would jump on it if I were you. Mine have rusted bolts that would take a while to grind off because you aren't going to budge them when they've been like that since 2001. Maybe if they were torched red hot, but I don't have an acetylene torch.
My 3rd 'Reply' after this shows a diagram for the rear bumper assembly with the two separate bracket & arm pieces labeled #4 & #5