I just had this posted on my "want to buy" thread. If it the same as the Pelican part, it would be a very good deal. I have no affiliation, or any idea what kind of adapter ring it is.
http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/942407-wtb-sir-tools-ring-engine-stand-adapter.html#post9436052