Rear Bumper Alignment

I have a '71 Duster, and as can seen in the photo the rear bumper does not align correctly with the body. At first I thought it was because someone had raised the car using the bumper and had bent the mounting brackets. Before I remove the bumper and attempt to realign the mounting brackets, I have to ask if the brackets could be installed incorrectly? By that I mean are the brackets made specifically for each side, or are they interchangeable? Rather than try to realign them I am thinking I can remove them, switch sides and reinstall them and hopefully the bumper will align better with the body. Any advice will be appreciated.
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