My First 318 Rebuild

I'm not done with the heads, but I'm getting to the point where I might just have a shop go through them and put new guides and such in, it seems like that's a place where budget should be higher.
Anyways on to the bottom end, I cleaned up the conrods and got 3 that came out brown. It doesn't look like rust and it doesn't flake off or anything. I know nothing about the history of this engine so I'm not sure what I'm looking at.
Pictured is the one "normal color" one and the three brown ones

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