I bought my 74 2 liter about 3.5 years ago and checked the tune-up parts right away. They all looked brand new so I left them. Today I changed the plugs after 3 years (only about 8 - 9, 000 miles) and this is what they looked like. Kind of brownish gray. I've always heard that in the long run it's better to run rich than lean. Do you guys think this looks lean or good?

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It has a petronix and the cap & rotor look practically brand new.

Thanks in advance for your wisdom & insight!