I enjoy seeing these types of threads, getting good views of parts of the equipment that aren't normally visible, or seen only poorly. Doing that work looks highly enjoyable.
The C&S 4-wheel caboose is derived from the DSP&P waycar, isn't it? In that case it's a holdover from the "true" narrow gauge era (the 1870-1890 period) because these cars remained in use far longer than most stuff from that period lasted. They highlight the desire of the early narrow gauge movement to keep deadweight to a minimum. Railroad equipment has a way of gaining weight over the course of its lifetime and I've long wondered how much these cabooses ended up weighing vs their as-built condition.