An automobile packaging machine having a conveyor which travels over a fixed and closed path. A plurality of carriers are mounted at fixed intervals along the conveyor. A tray having a fixed physical dimensions, is mounted on the carrier to carry an object having the same dimensions. The tray is releasably locked onto the carrier by a detent and a set screw associated with interconnectors. A spring biased detent indexes the position of said tray on said carrier. Then, a set screw is tightened to lock the tray in place. This way trays may be changed quickly and easily.