The cars the Carter Brothers built new for Sierra Valley would have been for the last incarnation, and included both box and flat cars. The Oregon and California (SP's subsidiary that owned the narrow gauge Oregonian, Portland and Willamette Valley, Portland and Yanhill) cars probably included some Carter cars as well, as the Oregonian had purchased 175 cars from the Carters in 1880. The combined narrow gauge lines also has some cars built in the Seattle area and some flatcars built by SP in Sacramento.
Randy Hees