Rick- a couple of notes on your list of surviving SP equipment. The "tin box" is no longer at Mina. Rumors say it was preserved but I do not know by whom. There is a wood box body at Mina located on the hill above town. It is in very good shape and was for sale (as of 6/20) along with a trailer home and .37 acres for $18,000 obo...
The box car body supposedly located at Mt. Montgomery is not visible from the highway so I do not know if it still exists...
On a related note there were some rail related structures that were torn down in Luning in the past year.