Steve:
Your truck used 8 bolts, 3/8 diameter, 4 inches long to mount the bed to the frame. Only two of the boards have the mounting holes. I do not have any plans for that truck. We have general instructions on the website
http://www.mar-k.com/drilling_mounting_holes.html for drilling the holes and making the countersink recess for the offset washer. Use these instructions for a guide and mark the hole locations directly from the frame of your truck. That way, the holes will exactly line up. The front pair of holes and the rear two pairs of holes are 31-3/4" apart (side to side) and the second pair back from the cab are 37-3/4" apart and positioned 23-7/8" back from the front set of holes. You can verify these spacings on your frame before drilling to be sure. Have the bed sitting on the frame correctly when you mark for the holes, mark the holes right up through the cross sills, and remove the two boards and drill the holes.
Good luck with your project.
Mar-Ktech