Suburban backup light housing -help !

[Franks 72]

Just starting to reassemble sheet metal backup light housing to body and noticed that the housing is not symetrical. It is wider on one side to account for shape in body. I didnt notice this when I disassembled them and now am stuck. Anyone got a close up of backup light assembly without the lens in? Do the rounded corners on the housing insert face left ,right , up or down (see photo for better explanation) . Thanks for your help !