67-72 step side tail question

[atm70chevy]

Can someone please help me with how the tail lights are mounted? I thought this would be a simple bolt on but with me nothing is simple... I have the tail light bracket but something either isn’t right with the holes in the bracket or on my bed because they will not line up. I looked in the assembly manual and cannot find them anywhere in it. I took my old ones off years ago and didn’t take pictures or keep the old brackets.

Thanks,
Anthony