In 1978, Thomas made a major change to the production of the Saf-T-Liner ER. Coinciding with a design update, Thomas introduced a company-sourced chassis, along with the front-engine Saf-T-Liner EF. With the introduction of the EF, Thomas became the first school bus manufacturer to produce its own chassis for both front and rear-engine school buses, ahead of Blue Bird by a decade (California manufacturers Crown Coach and Gillig Corporation had not produced a front-engine school bus since before World War II). As a competitor to the Blue Bird Mini Bird and Carpenter Cadet, Thomas reintroduced the Mighty Mite as a Type B bus, a school bus body paired with a stripped chassis.