For the 54 bed, the cross sills are at 2-1/2", 26-11/16" and 53-11/16" measured back from the front bed panel or the front edge of the wood, and there should be an angle strip bolt hole at each of those locations. There should be a bed to frame bolt hole in the frame at the 53-11/16 cross sill. The bed does not have a bolt to the frame through the 26-11/16 cross sill.

As stated in this quote from another post; "The bed does not have a bolt to the frame through the 26-11/16 cross sill".

There is a hole in the top of my frame at this location. It is smaller than the bed to frame bolt holes. Is this hole used to bolt the rubber pad sill support to the frame at this location. Or is there only 3-pads per side on a 54?

54 Chevy build pics.