FYI, there was a member who made his own bed sides that were modeled after the original ones by welding exhaust tubing of the correct size to the angled top. One could make a bed of any length, but you'd either need a 10' sheet metal brake or other method to make the bend in the top of the bed side for a 9' bed. The stake pockets can be bought from Mar-K or other vendors and welded on to the fabricated bed sides.
[on edit] Found it in the Tech tips
HERE