I added some seat belt photos for the HMMWV to my site. These are pictures of the newer 3-point seat belts, similar to the ones found in the standard car.
http://www.armorama.com/modules.php?set_albumName=albut94&op=modload&name=gallery&file=index&include=view_album.php
Dozens of detailed interior and exterior shots of various HMMWVs should help the builder fully accurize any of the various HMMWV kits. Better than any HMMWV book on the market and cheaper too.
Edited: should work now.