Question about bed bolts

[mocwon]

Got the '72 short bed in final primer and mocked up to fit the sheet metal and noticed an issue with the bed bolts. This truck started out life as a '72 GMC long bed and is ending up a '72 Chevy short bed so it's a conglomeration of various years of parts. When bolting a '67 short wide bed with a steel floor to a '69 frame two of the eight bed bolt holes don't line up with the frame. In fact, they are offset to the point that I would need to make offset brackets for them to work. Is this due to a difference between '67 and '69 beds, am I missing factory brackets made for this or something else

[mocwon]

ttt