It's a spec number for the grade of bolt. I don't remember if it's a ASTM number or a SAE number, but it's something like that. It's usually used on stainless steel bolts. I can't really see the number on these, but it looks like they may be 304 stainless.
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Freddie
1969 Camaro RS/SS396 (427) 4 speed
Last edited by big gear head; 07-29-2018 at 11:31 PM.
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