Why is one 340 connecting rod bronze color?

These are the comments I found on google...

dipped in copper at the factory to bring it into weight specs.
the copper flash plating was to fix rods that got a few tenths too big when they were honing the big end

GM, and Chrysler do it quite a bit, though I cant say I have ever seen a copper coated Ford rod. It was done at the factory to save rods that were finished just a hair too big. Dip them in the copper and you can get them back to the correct size. I do not beleive any rebuilders do it, it would not be cost effective. I bet I see at least 5 or 6 rods each year that way. Does not seem to hurt anything at all.