05' Sportster back fender doesn't have 3 holes?

I am trying to add a passenger pillion to my sportster low 05 stock solo
seat. However, my back fender only has the front 2 holes in it? Because of
this I can't install the final screw that holds the back of the pillion
down. How do I know what fender I have or how do I get that seat down? It
was purchased used and has a custom paint job, but the hole should still be
there?

Any help would be appreciated.