Most of the American-manufactured unibody automobiles used torque boxes in their vehicle design to reduce vibrations and chassis flex, with the exception of the Chevy II which had a bolt-on front apron (erroneously referred to as a subframe). American Motors (with its partner Renault) during the late 1970s incorporated unibody construction when designing the Jeep Cherokee (XJ) platform using the manufacturing principles (unisides, floorpan with integrated frame rails and crumple zones, and roof panel) used in its passenger cars, such as the Hornets and all-wheel-drive Eagles for a new type of frame called the "Uniframe [...] a robust stamped steel frame welded to a strong unit-body structure, giving the strength of a conventional heavy frame with the weight advantages of Unibody construction." This design was also used with the XJC concept developed by American Motors prior to its absorption by Chrysler, which later became the Jeep Grand Cherokee (ZJ). The design is still in use in modern-day sport utility vehicles such as the Jeep Grand Cherokee.