Try this link.
http://67-72chevytrucks.com/vboard/s...d.php?t=581185
And... from Mar-K
"The first cross sill connects to the second bed strip hole that is 3-3/8 inches back from the front of the bed. The second cross sill connects to the third bed strip hole that is 15-3/8 inches back from the front. The third cross sill attaches to the bed strip hole 26-3/4 inches from the front of the bed. The fourth cross sill connects to the eighth bed strip hole at 72-1/2 inches from the front, which coincides with the rear of the wheel well. The fifth cross sill connects to the ninth bed strip hole at 83 inches from the front. There are two smaller cross members located at the front or beginning of the wheel well and at 60-1/8 inches from the front of the bed. One reinforcement strip is 72” and one is 49-1/2”. Attach these reinforcement strips to the bolts from the bed sides and the wheel well. Mount the 72” at the front of the wheel well and the 49-1/2” reinforcement strip fits between the wheelhouses at 60-1/8 inches."