You're right..
I just got off the phone with New Castle Battery,(TurboStart.com),they answered the phone,"Commercial Battery."
I asked what happened to New Castle Battery?..she replied they went out of Business at the End of June.
I asked if they now sell what New Castle used to & she said yes,but not any of the Antique Car batteries at all.
I then called Antique Auto Battery in Ohio 1-800-426-7580.
They are now the GM License holder to the Antique Delco Batteries.They said they get $230 for the New Sealed R-59 & it will be at least 2 weeks or more waiting list.
The R-59 Open Lead acid is $140 & readily available.
They can stamp any Date on them you wish.