Updated 3 October 2012
The NDSF is a side-dumping wagon, and seems to come in two types distinguished by how much angular support the sides have. You can find some useful information on these on Railpage, including a friend’s photos of them in action, and some line drawings of the Goninan built variety – http://www.railpage.com.au/f-t11339456-s0-0-asc.htm
No model exists that I know of. Anyway, here are my photos …
Interestingly, 1470 has recently had the side doors welded shut, the hydrolic equipment removed, painted orange, and recoded NACF 1470B. A photo can be found on wagonfreak’s Rollingstock News blog.