the angles are part of the bed sides, the 'skids' are the loose strips you'd buy that fit the slots in the board edges to hold the boards against the cross sills .... the skids have bolt holes only where they are bolted to the cross sills - from the factory there are no bolts thru the skids between the cross sills, although there may be/are "extra" holes in the angles, and of course after 50+ years there may be any number of holes added for someones special purpose [like yours!]
the 55.2 - 66 step beds are the same, but the cross sill placement varies between the series because the frames differ, you might have a bed some one got from a 60's truck and put on their 56, adding extra holes in the process - I put a bed from a 63-66 on a 58 frame and had to redrill some mounting holes in the frame cuz cross sill position was different
"bolts with only washers" could refer to the bolts that hold the bed on the frame, which have the large square hole washers and don't go thru the skids, but do line up with the cross sills
at any rate, a fabricated framework [instead of "extra" cross-sills] will be required to make the bed strong enough to be a dumper, so make it to suit the hole spacing in standard 56 shortbed skids [6'], no extra bolt holes required in them, the extra holes for added cross braces will be mount holes thru the wood, you just need extra square-hole washers for that
Bill
