I have one of these in yellow, one in gray and two in black. I don't have any pictures of the black ones because the yellow and the gray photograph so much better. And they are exactly the same except for the color.
I modeled these after a hopper in the Walthers catalog. I'm relatively pleased with them, though I'd like the ladder to look somewhat less heavy. The look nice and beefy trailing along behind my SD70 engine.
I built these well over a year ago. I don't recall exactly when. And I feel deep in my heart, that I didn't intentionally copy anybody's ideas. But I'm sure I've been affected subconsciously by other Lego people's work such as Steve Barile, Ben Fleskes and Larry Pieniazek just to name a few.
Here's a tanker that is a direct copyright violation of something Steve Barile has been working on. The bas that its sitting on is made with two of those Explorien triangle grate plate like pieces connected together with a couple of 2x plates. It actually looks really good. (Mine doesn't because of the color issue, but Steve's does!)