Following its order of 525 GM New Looks in 1972, the CTA purchased an additional 545 of the buses in 1973.

The buses were painted in the CTA’s two-tone green scheme, although some where eventually repainted in the CTA’s white, red, and blue paint scheme which was introduced in 1987.

While portions of the 7400-series were retired throughout 1990 and 1991, the entire series was not retired until 1996.