Pretty model with good proportions except for the fact that they feel light. They may be ok, almost certainly are, however the Orient Models Productions OBF weighs almost exactly the same, and does need a metal weight that is placed on the floor (neat fit) of an unloaded wagon, it is painted to hide it away. I will let you know how these go without the extra weight.
Interestingly I started to compare the Auscision GY to the SDS one and got a fright when I saw the difference in the leaf spring suspension, but as usual Steve and the fellas at SDS got it right.. See here.. EDIT: The Auscision GY leaf springs are also correct and match the version of the GY they modeled. I did not realize the springs varied over the different series of wagons.
from SDS pages.