Round Bed Holes- What are They?

[Too Slow '90]

I am installing the bed kit in my 60 short bed fleetside and have too many holes! There are 2 holes in front of each wheel well that are round instead of square. Since they are not made for the square shoulder bed carriage bolts I'm not sure what they are for. I couldn't find anything about them in the manual. I would appreciate someone telling me what they are for and yes this is my first rodeo. Thanks.