What is this bracket for??

[leftybass209]

I pulled this bracket off swearing I didn't need to label the bag it was in, it's unique so I should remember where it goes I told myself. Well...... I'm lost. I know it goes on the drivers' side, and it appears to be something for the parking brake, but I'm lost as to where or what it does. I tried lining up the holes on various parts of the frame with no luck. It's from a 69 2wd short bed.