In 1920, Leo's brother Chester Gillig joined the company and introduced and patented the "California Top" roof construction style consisting of a hard-top roof and sliding windows. The company's name was changed at this time as well to Gillig Bros. In the late 1920s, Gillig starting producing pleasure boats and heavy trucks, and produced their first school bus in 1932. In 1937, Gillig introduced their first transit-style (flat front) school bus, and in 1938 the company moved to Hayward, CA. In 1957, Gillig purchased Pacific Bus division of Kenworth Truck Company, and by that time the company was devoted almost entirely to the production of school buses. In 1959, Gillig pioneered the diesel-powered rear-engined transit style school bus with the release of the C-series Transit Coach, and wit