I hope this time I posted in the right form. The date on this 1983 penny seems to have a plug, this is what I have called when I saw the bottom half of the 8 in the date was filled in. Here is a picture of it.
The metal of the planchet is forced into any opening in the surface of the die during the strike. When the post in the lower half of the 8 on this die broke off and fell out of the die, it left an area that was slightly deeper than the rest of the date. That's why the lower half of the 8 in the date is slightly higher than the other digits on the resulting coins.
I often hear this referred to as "Extra Metal" on the coin, but it's just that the normal metal from the planchet was pressed into the new hole in the die. Also, keep in mind that every coin struck with this obverse die after the post dropped out will have the same filled lower loop on the 8. This is the reason that it's not uncommon to see and, even though it's interesting, doesn't add value to the coin.
ANA Member ID: 3203813 - CONECA Member ID: N-5637 "Shine, shine a Roosevelt dime. All the way to Baltimore and runnin' out of time." Tom Waits-Clap Hands