Wikipedia
Trucolor was a color motion picture process used and owned by Consolidated Film Industries division of Republic Pictures. It was introduced as a replacement for Consolidated's own Magnacolor process.
Republic used Trucolor mostly for its westerns, through the 1940s and early 1950s. The premiere Trucolor release was Out California Way (1946) and the last film photographed in the process was Spoilers of the Forest (1957). With the advent of Eastmancolor and Ansco color films, which gave better results at a cheaper price, Trucolor was abandoned, coincidentally at the same time as Republic's demise.
At the time of its introduction, Trucolor was a two-color subtractive color process. Approximately three years later the capability of the process was expanded to include a three-color release system which utilized DuPont film stock. The DuPont film was later replaced by Eastman Kodak film stock. Thus, in its life span of approximately twelve years, the Trucolor process was in reality three distinct systems by which color release prints were made, all bearing the same screen credit, “Trucolor”.