I have a 1966 filled die reverse penny without the word "states" and without the "O" in of America. Is this rare?
It might turn an error collector on a little if it's in decent condition but it isn't "rare," at least not as how you're describing it.
If this guy is selling it, then yes, yes it is... It's very rare and will never be available from the mint again. So buy it now, I only have about 12,000,000 left, and once they are gone, they're gone forever...
...and if you order with your credit card during the commercial you can have my green tie, my green shirt, and this green plant behind me, at no extra charge, just pay shipping and handling.
rare no, without seeing photo's i'll guess its a greased filled die . Hang onto it though as it is still an error although a very common one
Possibly grease filled die but that area is also opposite the base of the bust which "soaks up" a lot of metal and results in weakness in the area mentioned if the strike is a little weak.