The battery hold downs for both engine and frame are wedge shaped hard plastic pieces that are secured via a long thin bolt to a captured nut in the bottom of the tray. It wedges against the inside of the box and the battery while pressing down on a protruding edge on the side battery case near the bottom. It is rather blind in installation, not easy and the bolt can cross thread w the nut.
Cover for frame mounted battery box is a plastic half clam shaped piece that is secured by screws in clips on the box.
I will dig around for some pictures.