Here is a nice Kevlar Tandem for sale, It does look like an X17 but the seller can't find a tag on it.
http://www.ebay.com/itm/251704909779?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT
http://www.ebay.com/itm/251704909779?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT