Includes road numbers 1841, 1842, 1845, 1846, 1849, 1850
In 1968, the Southern Pacific railroad purchased from Gunderson (GBEC) a new bulkhead design - a straight tapered bulkhead design. The straight tapered bulkheads flat cars had 57'-0" loading platforms and were classified as class F-70-50. The SP followed up with two additional orders from ACF as SP class F-70-59 and F-70-61. The ACF cars were identical to the GBEC ones. These bulkhead flat cars carrried plasterboard and lumber.