Prior to its reorganization as Thomas Built Buses in 1972, Thomas Car Works produced both front and rear-engined transit-style school buses to compete with other manufacturers. As was the common practice during the era, the chassis was outsourced to another manufacturer. Thomas offered its transit-style buses on a wide variety of chassis in comparison to other manufacturers (changing between Dodge, Ford, GMC, International Harvester, and Volvo). In contrast, Blue Bird, then the largest school bus manufacturer in the United States, manufactured its own chassis (as did West Coast manufacturer Gillig). In 1978, coinciding with an updated body design necessitated by federal school bus safety regulations, Thomas became its own chassis chassis manufacturer with the launch of the Saf-T-Liner EF a