59 3100 Rear Frame Help

[pgnavy]

Hey folks, I need a photo of an original 58 or 59 rear frame, with the location of the rear bumper bracket holes. I am installing a bumper and brackets and not sure which holes to use. Unfortunately PO made this one look like swiss cheese!
When I use holes numbered 3 and 7, the bumper looks like the photos below (a bit too far from the bed body). The frame schematic from GM seems to indicate hole #1 and #5 might be the original location? When I install in 1/5, the bumper rests against the rear fenders. Help appreciated.