The OP statement was about a 79 D filled MM you post a 76 with ( environmental damage) so I'm confused what's the connection between your 76 and his 79. Dave
On the filled 79-D sometimes it's just circulation. Sometimes it's an RPM. The filled D is very common, probably because of the shape. You will see it on nickels and dimes and quarters as well. It's usually nothing. I have no idea about the 1976 Philly.
