Yes, as I wrote it is in the game but it's not attached to the Snipers back.
It's not the wrong position, otherwise it would at least rotate with the snipers back:


"I created a simple skin for the razorback with SketchUp:"
I know that SketchUp isn't meant for modeling but I wanted to try it anyway. Props work fine and I thought the error might be somewhere else and can be fixed without Milkshape, 3dsMax, Cinema 4D, XSI or Blender.
Mmh ... I don't have it and I wouldn't buy it for some models. I'm too dumb to fully use and understand it anyway.
So this will be just another of my dozens of projects that got scrapped. Maybe someone can pick up that idea later again.