I am still searching our archives to see if they had a U-shaped dump body for that style frame so far it is just the V-style which in reality was the most common.
One thing that will need to be researched in some way is how the mine transported the ore. It is possible that they had 18' ga ore cars working in the mine & transferred the ore outside to the 30" ga car for processing hence the possibility for the v-style body. The U-shape style were typically used in close clearance situations for the most part.
A second possibility that car was used to transfer the junk rock from the mill to the gob piles. 30" ga gave it a larger capacity for the waste rock. A hoist may have been in use to pull this car up a slope to the top of the pile
I hope this helps a little.