SP leased some locomotives, coaches, and I believe cabooses to the standard gauge Nevada-California-Oregon. In Myrick's opus there are photos of the opening standard gauge train to Alturas with this standard gauge equipment lettered for the N-C-O.
A few years ago I reviewed some of the N-C-O accounting records that are in collection of California State RR Museum. These showed that ng locomotive #22 was returned to the capital accounts during the standard gauging and then leased to the Southern Pacific probably to go to Mina.
Brian Norden