One of the most common spoils wagons you will see are the rusty old NDCHs – however these come in two main types. The more common type are ex NOBX open wagons.
The majority seem to be rib-sided with flat panels where the doors used to be, however there is at least one with all flat panels. There is a mixture in the ends also – I believe the flat panelled wagon(s) have flat ends, where the rib-sided ones have either pressed or corrugated ends – some have one of each.
IDR Castings produce the former Scaleways kit of the flat panelled version which could also be kitbashed into the rib-sided versions, though kitbashing the AR Kits BDX/NOBX may also be a good option, saving applying the ribs, but requiring the sides to be cut down. I am taking the more tiresome path of scratchbuilding the rib sided versions.
Due to the number of photos, I’ll have to split it across two posts …