So I haven't searched recently. When I was comparing with shackles that would fit the Acco chain, the Whichard was stronger for a pin and shackled shackle body that would fit.

There are many galvanized shackles that are rated for simple lifting with higher strength steel -- but I could not get it through the chain.

Your observation appears correct for your search Dave. Many galvanized off the self shackles being rated higher (whether the true quality control is there for boat stuff matching rigging (industrial) lifting applications is a different question. From an industrial lifting application manufacturer with a certification, you can depend more on the working load (after variable safety factors have been applied) vs. maximum breaking strength, etc.

The bulk of industrial applications just go with galvanized because appearance and a bit of rust doesn't justify the extra cost for higher strength steel.