A shear is a shear, that wouldn't have anything to do with the SS crumbling. Might be a good idea to pass this experience on to the C37 owners group if there is one. I would want to know if I had one.
Implied in your posts in this thread is that there is something unique about the material or fabrication method Pacific Seacraft used for their chainplates.
According to a PSC 34 brochure (I believe this also applies to the 37) . . .
Chain plates are ¼" thick and 2" wide type 304
stainless steel thru-fastened to the hull with ½"
stainless steel bolts and full hacking plates.
Perhaps anyone with similar chainplates of that age should be concerned? Why aren't we seeing much more widespread problems in actual use if this is a real issue?