I am no expert in metals but in a quick search in defender for 3/8 shackles I found Crosby Galvanized with working load of 2 metric tons (4400 lb) and Wichard SS D style shackle at 3344 lb and the superior design for side loads SS Wichard bow shackle at 1344 lb. What SS shackle do you use that exceeds the rating of a quality galvanized? I prefer Galvanized in any case since my anchor and chain is galvanized and I don't want to introduce a dissimilar metal in seawater.. hell I seize the shackle with galvanized wire.