Should be the black base, single snorkle, chrome lid air cleaner for the 325. The 360HP and 375HP went with the open element, chrome lid type. Valve covers for 66 should be chrome. Best I can recall the painted covers started appearing either during the 71 model year on the non SS BB cars or the next year as the de-emphasis on performance took hold. The covers may have been painted on the 60s Impalas, etc. big cars, but should not be on 60s Chevelles. Someone check me on that part!
John Walker