splintered chest (drop from sastasha hm--the drop itself not the finished "dead man's chest" furniture) is an r90 (armorer) that gives darksteel ingots, wolfram squares, darksteel rivets, and 1-2 FC 3's (maybe possibly 3 FC III's but I never saw it in over 100 desynths)

Presumably same mats from desynthing dead man's chest but you'd never do that since that synth takes 3 splintered chests...