Looking at the right valve cover I see a small bracket that holds the air cleaner on. I can't make out the left one. Because it has a small bracket attached to the valve cover and a rubber mount on the bracket indicates it is a "small block" which will either be a 380 or a 420. All the 420s I have seen have black valve covers but I know they could have been changed. The 500 and 560 were "big blocks" and don't use the extra bracket for the air cleaner mounts as they are a little wider. They put the rubber mount directly on the VC. As for the timing chain, a lot 380s were converted to the double row chain the first time the single row chain breakes.

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84 500 SEL (307,xxx miles)