Faced with an aging fleet and growing wartime traffic, the Southern Pacific began a major caboose building program in 1917. The new design was the first with a Harriman Common Standard class designation, C-30-1, to indicate car type (C for caboose), weight (30 tons) and design series number (1 for first series). Though similar to earlier CA series cars, the new design incorporated several improvements including a riveted steel underframe. This made the cars sturdier and safer, especially on runs where helpers pushed trains upgrade. In the next ten years, SP built over 600 C-30-1s, making them the largest group of cabooses in service on the railroad and its subsidiary lines. They were also long-lived, working all types of freight assignments into the 1960s.
 
Gold Line(TM) models feature a detailed plastic body, RP-25 turned metal wheelsets, correct trucks, working McHenry knuckle couplers and interior. A complete set of add-on grab irons is provided, and molded drill starter points on the body make installation easy.