here is some info from Bob Paoa at the Hawaii Railway Society:
I believe there were 87 of this class of cars built in 1928. The numbers were in the 600-700 series. This may well be the sole survivor of the lot. The HRS owns a 30 ft, 10 ton, inside braced box car which is also the last of its kind. The CC&NRy car was designed by John A. Hughes, master car builder for OR&L, and constructed in the railway's shop in Honolulu. A drawing of this series car appeared in the NG Gazette, Mar-Apr 1990. Cars had 26 inch wheels. There were also 34 ft IS braced box cars of the same design but were limited to 10 ton capacity.