Abstract: A hook structure which forms part of a device for tying down motor vehicles upon vehicle transports such as railroad cars, trailers, and the like. The hook structure is capable of being inserted through an elongated slot in the frame of a motor vehicle and comprises a body having means at opposite edges for the attachment of two chains. A bolt is rotatably connected to the body and terminates in an elongated cross-head. The bolt is capable of being inserted head first into the slot and retained therein when turned 90.degree.. The bolt has a square shank portion under the head which normally engages the slot to prevent rotation. The bolt shank has a circular portion more remote from the head to permit the bolt to be rotated when inserted farther into the slot.