 Similar in layout to the frame adopted for the 1957 Cadillac, it featured box-section side rails and a boxed front cross member that bowed under the engine, these "X-frames" were used on other 1958 to 1964 Chevys, as well as Cadillac.The rear was tied together by a channel-section cross member.This design was later criticized as providing less protection in the event of a side impact collision, but would persevere until 1965.