I built a second one in Redish Brown and Dark Bluish Gray
This Flatar design was modified from Jeramy Spurgeon's design "50' Flat Car" which can be downloaded from Railbrick.com
First I widen it to 8 studs, then added a little more length so that I could add corner steps, and used my arch-bar trucks. I also fixed the problem of "break-a-part" that Tony noted in his review. I fixed this by adding a 30414 Brick, Modified 1 x 4 with 4 Studs on One Side outside of the 3700 Technic, Brick 1 x 2 with Hole at each end, locking to the "deck" plates.