The boss is from the nose of a band new Powermaster mini starter. The seller installed it then didn't bother to tighten the bolts... which I discovered when it stopped turning the engine over. I got the correct length grade 8 bolts when I discovered why it stopped turning the engine over. It's only now that I see he FUBARed a perfectly good starter. Ugh. Thought about trying to weld it back on, but it's cast AL and so probably will be too dirty to weld, plus I'd have to make a fixture to locate the boss. Hopefully it lines up close enough when it goes back in.