Cast iron skillet identification

I have two unmarked number 8 cast iron skillets that belonged to my grandmother and I would like to inquire if anyone here would be able to help with their identification. I'm 60 years old and I can remember her cooking with these two skillets when I was a little boy and she used them until she went into a nursing home in 1992. She passed in 1997. I believe she had them for some time before I was born.

The first skillet has a smooth bottom and is marked "10 1/2 INCH SKILLET" and has "Z 2" on the underside. Marked with a recessed "8" on top of handle.

The second skillet is marked "Iron Age" on the underside and below that is marked "No. 8". It has a heat ring with four notches in them. Also has a recessed "8" on top of handle.

Both skillets are smooth finish on the inside and have thinner walls than on new skillets.

Any help or suggestions is greatly appreciated.