Boxcar 1C was the tool car for the Mina wreck -- or in SP parlance "relief" -- train based around the hand-powered derrick #1. This is the reason for the grab irons and strip step next to the door. On the SP the cars in a relief train were numbered for the derrick with letters added.
The Relief train was disassembled when the narrow gauge was abandoned in 1938 over Montgomery Pass. It is said that the derrick could not pass through the tunnel. The derrick was broken up at Mina in July, 1938, several months after the last ng train left Mina.
Wheel car 1A became a simple flat car; boarding car 1B, a former combine, became caboose 16 and then caboose 401; boarding car 1D, once a "box car caboose," was vacated (retired) in July 1940 and broken up 1-3-41.
Brian Norden