Fleetside Bed Inner Rear Splash Shield Mounting?

[Old_Truck_Fan]

Hi Guys, I purchased a reproduction bed with a steel floor and am trying to fit the rear splash shields that mount behind the rear tires. The bedside has a weld nut for one of the mounting features but the bed floor brace only has through holes (see arrows). Should a weld nut have been used in these locations? Or am I missing something. Thanks for your help.